which is the best ?

The OnePlus, Xiaomi Mi and Samsung Galaxy S21 are among the best proposals for Android smartphones in 2021. But which one do you need? Which of the three is the best? Answer in this comparison.

OnePlus 9 Mi 11 Galaxy S21

The OnePlus 9 was officially unveiled by the Chinese manufacturer, which unveils its first models of smartphones of the 2021 generation. The opportunity to submit the device to the exercise of the comparison with two other references of the Android ecosystem positioned on the same segment: Xiaomi’s Mi 11 and Samsung’s Galaxy S21. So which of the three mobiles suits you and best meets your needs? Find out in the following lines!

OnePlus 9, Mi 11 and Galaxy S21 technical sheet

In this table you will find a first overview of the similarities and differences between the three smartphone models. We come back to the strengths and weaknesses of each in more detail in the next paragraphs.

Oneplus 9 Xiaomi mi 11 Galaxy s21
Screen 6.55 “
2400 x 1080 pixels
20: 9
120 Hz
20: 9
120 Hz
HDR10 +
6.81 “
1440 x 3200 pixels
20: 9
120 Hz
HDR10 +
6.2 “
2400 x 1080 pixels
20: 9
120 Hz
HDR10 +
Chipset Qualcomm Snapdragon 888 (5nm) Qualcomm Snapdragon 888 (5nm) Exynos 2100 (5nm)
BONE Android 11 + OxygenOS 11 Android 11 + MIUI 12.5 Android 11 + One UI 3.1
RAM 8 or 12 GB 8 or 12 GB 8 GB
Storage 128/256 GB 128/256 GB 128/256 GB
microSD No No No
Main sensor 48 MP wide angle f / 1.8
50 MP ultra wide-angle f / 2.2
2 MP monochrome
108 MP, f / 1.9, 26mm (main), 1 / 1.33 “, 0.8µm, PDAF, OIS
13 MP, f / 2.4, 123˚ (wide angle), 1 / 3.06 “, 1.12µm
5 MP, f / 2.4, (macro), 1 / 5.0 “, 1.12µm
12 MP wide angle f / 1.8
12 MP ultra wide angle f / 2.2
64 MP telephoto f / 2.0
Selfie sensor 16 MP, f / 2.4 20 MP, 27mm, 1 / 3.4 “, 0.8µm 10 MP (f / 2.2)
Drums 4500 mAh
Warp Charge 65 watts
Wireless charging 15W
4600 mAh
55 watt wired fast charge
50W wireless fast charge
Fast reverse charge 10W
4000 mAh
25W wired charging
Wireless charging 15W
4.5W reverse fast charge
5G Yes Yes Yes
Biometrics Optical impression scanner under the screen Optical impression scanner under the screen Ultrasonic footprint scanner under the screen
Water resistance No No IP68


The OnePlus 9 sports dimensions of 160 x 74.2 x 8.7mm. It is more imposing in all aspects than the Galaxy S21, more compact with its 151.7 x 71.2 x 7.9 mm. On the other hand, it is slightly shorter and wider than the Xiaomi Mi 11 (164.3 x 74.6 x 8.1 mm), but thicker. On the scale, the two Chinese smartphones display a little less than 200 grams: 192 for the OnePlus 9 and 196 for the Mi 11. The Galaxy S21 is lighter with its 169 grams.

For the materials used, OnePlus and Xiaomi live up to the promise of premium with a Corning Gorilla Glass back. Samsung is more disappointing by relying on a plastic rear panel, admittedly of good quality, but which cannot claim to replace glass. The slabs of the three devices are protected by a latest generation Gorilla Glass Victus glass protection.

Oneplus 9

Only the Galaxy S21 is certified IP68 water and dust resistant, but that does not mean that the OnePlus 9 and Xiaomi Mi 11 are less waterproof: the manufacturers have chosen not to pay for the certification in order to reduce costs. Each mobile has a fingerprint reader under the screen, with ultrasonic technology from Samsung and optical technology from OnePlus and Xiaomi.

Thanks to its curved screen and thin borders, the Mi 11 offers the best screen-to-body ratio of the three proposals with a screen occupancy rate of 91.4%. The frame of the OnePlus 9 and Galaxy S21 is a little more visible. The front camera is housed in a punch in all three cases: at the top center at Samsung and in the upper left corner at Xiaomi and OnePlus.

Xiaomi mi 11
Xiaomi mi 11

At the back, the photo unit is located at the top left, with each time three sensors and an LED Flash. Each setup has its peculiarities. Samsung glued the block comprising the three modules following each other in the direction of the height at the edge with its S21 and placed the Flash light outside of it. Everything is discreet and takes up little space on the rear surface of the device. At OnePlus, the triple sensor is also positioned vertically, but less at the edge and with the LED Flash inside. The Mi 11 offers a more square than rectangular shape with the two most important sensors on the left as well as the other camera and the LED Flash next to it. This is undoubtedly the most original option.

Finally, the colors. The OnePlus 9 is available in Glossy Purple, Matte Black, or Matte Blue. The Mi 11 comes in blue, white and gray. There are also special editions offering more original gold and purple colors. The Galaxy S21 can be purchased in gray, white, purple, and pink.

Galaxy s21
The Galaxy S21

Winner: Xiaomi Mi 11 for curved lovers, Galaxy S21 for compact fans, OnePlus 9 for a compromise, it’s a matter of preference here.


If all three smartphones are equipped with a AMOLED technology, there are disparities in the functionalities offered by the different panels. In terms of the size of the diagonal in the first place: the Galaxy S21 is a small format with its 6.2-inch screen, while the OnePlus 9 is more or less average with 6.55 inches. The Mi 11 looks like a monster with its slab 6.81 inch. But as seen previously, the smartphone itself is ultimately not much more imposing than the OnePlus 9 thanks to its thin borders.

The Mi 11 also has the best screen resolution: around 515 pixels per inch thanks to its image definition. Quad HD + 3200 x 1440p. The OnePlus 9 and Galaxy S21, for their part, display Full HD + 2400 x 1080p quality, i.e. a density of 402 pixels per inch on the first and 421 ppi for the second. Otherwise, we find the same stretched 20: 9 aspect ratio, a refresh rate of 120 Hz and HDR10 + compatibility on all three models. Maximum brightness in HDR reaches 1,100 nits on the OnePlus 9, 1,300 nits on the Galaxy S21 and 1,500 nits on the Xiaomi Mi 11.

Xiaomi mi 11
Xiaomi mi 11

Winner: Xiaomi Mi 11


This is one of the great novelties of this year, the arrival of high-end chips engraved in 5nm, even more powerful and energy efficient. The OnePlus 9 and Xiaomi Mi 11 are equipped with the Qualcomm Snapdragon 888 SoC, while Samsung preferred its home platform Exynos 2100 for the European version of its Galaxy S21. Premium components that deliver premium performance as well as 5G compatibility. At this little game, the Snapdragon 888 fares slightly better than the Exynos 2100 when it comes to raw power. Samsung has made up some of its lag on this generation, but a gap still exists between its Exynos and the Snapdragon.

The Xiaomi Mi 11 is the most powerful Android smartphone currently available in France, quite far ahead of the Galaxy S21 on the AnTuTu benchmarks (708,990 against 601,031). The performance of the OnePlus 9 has yet to be measured, but it should score close to that of the Mi 11.

qualcomm snapdragon 888

All three smartphones come with 8 GB of RAM, but the OnePlus 9 and Xiaomi Mi 11 are also available in a more muscular configuration with 12 GB of RAM. As for storage space, it’s a perfect tie. The three mobiles are based on UFS 3.1 technology and offer two internal memory capacity options: 128 or 256 GB. No location for memory expansion via microSD is to be reported on these smartphones.

Winner: OnePlus 9 and Xiaomi Mi 11

Battery, autonomy and recharging

Smaller than its cronies, the Galaxy S21 logically embeds the least imposing battery, with a capacity of 4000 mAh. The OnePlus 9 goes up to 4500 mAh and the Xiaomi Mi 11 to 4600 mAh. Of course, the autonomy of a mobile does not depend only on the size of its battery, but also on its consumption and its optimization. The Mi 11 is for example very greedy with its large QHD + screen to power. Considering its battery, its only FHD + display, its efficient Snapdragon 888 chip, and OnePlus’ serious history of optimization, the OnePlus 9 seems to be ahead in terms of battery life on paper. Our test will tell you more about it on its behavior in real use.

When it comes to charging with cable, OnePlus is often one step ahead. It proves it once again with its wired charging technology Warp Charge 65T to 65W. The manufacturer announces a day of use in just 15 minutes of charging and a full recharge from 0 to 100% in 29 minutes. The Mi 11 delivers a charge of up to 55W allowing the smartphone to be recharged from 0 to 100% in 45 minutes. The Galaxy S21 is the bad student on this aspect with a 25W wired charging. And to make matters worse, the smartphone comes without a charger from Samsung.

Galaxy S21 design
The Galaxy S21

OnePlus, on the other hand, has long lagged behind in wireless charging, which is also true. We are entitled to a wireless Qi charging of 15W, and without reverse charging functionality. The Galaxy S21 offers the same 15W power, but with a 4.5W powerbank function to charge other devices with the smartphone battery. It is the Mi 11 that stands out in this category with its super fast 50W wireless charging, coupled with reverse charging up to 10W.

Winner: OnePlus 9 wired, Mi 11 wireless


The great weak point of OnePlus smartphones since the brand’s beginnings is undoubtedly the photo. With each new iteration, the manufacturer praises its progress, without necessarily seeing a marked phenomenon of catching up with the competition. This time, OnePlus wants to be taken seriously in the photo and has woven a partnership with the specialist Hasselblad for optics, as Huawei can do with Leica for example.

The OnePlus 9 relies on a main sensor 48 MP Sony IMX689 with f / 1.8 aperture and EIS stabilization, associated with a 50 MP f / 2.2 ultra-wide-angle module (the same as on the OnePlus 9 Pro) and a 2 MP monochrome lens which will notably be dedicated to measuring depth of field. The 16 MP f / 2.4 front camera supports selfies.

OnePlus 9 photo video
The OnePlus 9

The Xiaomi Mi 11 has a 108 MP photo sensor with f / 1.9 aperture and optical stabilization. It allows you to take photos in a very high definition and level of detail, which is used to zoom in the image, to print large-format photos or for photo retouching. The smartphone otherwise uses the pixel binning technique to group four pixels into one in order to capture more light and improve quality. The camera then shoots in 27 MP.

The Mi 11 is also equipped with a 13 MP f / 2.4 ultra wide-angle module (123 °) and a 5 MP f / 2.4 macro lens in order to take better close-ups.

The Galaxy S21 offers a 12 MP f / 1.8 wide-angle main sensor and a 12 MP f / 2.2 ultra-wide-angle (120 °). Unlike its competitors, it offers a telephoto 64 MP, f / 2.0 and OIS allowing a slight optical zoom of 1.1x and a hybrid zoom up to 3x. As usual, Samsung’s photo software processing is very convincing.

Xiaomi mi 11
The Xiaomi Mi 11

Finally comes the question of video capabilities. The OnePlus 9 can record in 8K at 30 frames per second and in 4K at 30 or 60 fps. It has a slow-motion mode at 480 frames per second (in 720) or 240 fps (in 1080p) and a time-lapse mode up to 4K at 30 fps. The Mi 11 also shoots in 8K, at 24 or 30 fps, and in 4K at 30 or 60 fps. Slow motion is limited to 240 frames per second, at 1080p. As for the Galaxy S21, it offers 8K video recording at 24 fps, 4K at 30 or 60 fps and a slow-motion mode more advanced than the competition, going up to 960 fps in 720p.

Winner: Xiaomi Mi 11 or Galaxy S21


All three smartphones are based on Android 11, the latest version of Google’s mobile operating system. But the interfaces and functionalities remain different since each mobile benefits from a different overlay, each bringing its advantages and disadvantages.

The most complete seems to us to be One UI from Samsung, which in addition to offering smooth navigation, has features that can be very practical as needed, such as DeX mode allowing you to connect your smartphone to a monitor or TV for a desktop experience on the big screen with his mobile.

one ui

But OxygenOS of OnePlus is also a very good option and remains one of the most beloved overlays in the Android community. According to U.S, MIUI from Xiaomi is still below the other two, despite good improvements in recent years. But the Mi 11 still offers a completely decent software environment.

Winner: OnePlus 9 or Galaxy S21


The OnePlus 9 is marketed at a price of 719 euros in its 8/128 GB configuration and at a price of 819 euros for its 12/256 GB variant.

The Xiaomi Mi 11 is slightly more expensive: count 799 euros in 8/128 GB and 899 euros in 12/256 GB.

The Samsung Galaxy S21 is the least affordable of the smartphones presented in this comparison. It’s sold 859 euros with 128 GB of storage and 909 euros with 256 GB of internal memory.

The prices indicated are the official prices recommended by the manufacturers, excluding promotional offers.

Winner: OnePlus 9


In terms of value for money, the Galaxy S21 seems to us out of the race against its two competitors. It is more expensive and offers lower performance on several key criteria, such as the screen, the refill or the materials used (the only one to be equipped with a plastic rear panel and not glass). It may still be suitable for those who swear by One UI and Samsung services, or users looking for a compact size that is easy to handle.

Between the Mi 11 and the OnePlus 9, the choice is more difficult. The first city is more expensive, but also oriented a little more premium. Ultimately, your usage will guide you to the right decision. If you use wireless charging, the Mi 11 is very interesting, while both mobiles excel in wired charging and performance. The screen of the Mi 11 has a curved screen with a large diagonal and a QHD + definition, real assets. But some who can be satisfied with Full HD + will prefer a device easier to handle like the OnePlus 9. Then, it’s a matter of taste between OxygenOS and MIUI. For us, the interface of OnePlus is nicer than that of Xiaomi.

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