Xiaomi's Mi 9 is one of the leading candidates to usurp the throne. The Mi 9 matches the OnePlus 6T in some respects, from screen to in-display fingerprint sensor, but Xiaomi's phone also seemingly comes out ahead in some respects. Can Xiaomi beat OnePlus at its own game?
Here's what we think now that we've reviewed both handsets.
Design: Two of a kind
These are both sleek-looking handsets. In fact, they're nearly identical from the front. Both have teardrop notches atop the screen, with the 6T's sloped and the Mi 9's a bit more severe. Both have a smidge of bezel at the top and a slightly larger chin at the bottom, but it's the screen that dominates both faces.
On the back, the Xiaomi Mi 9 opts for a glossy finish while the OnePlus 6T frosts its own glass – and the cameras are center-mounted on the 6T, but on the left on the Mi 9. Overall, however, they're pretty close in overall design and execution.
Screen: Nearly identical
Again, the specs are very close here. The OnePlus 6T has a 6.41in 1080p AMOLED panel, while the Xiaomi Mi 9 opts for… a 6.39in 1080p AMOLED panel. Will you notice the .02in difference in size? No, we don't think so.
Both also have an in-display fingerprint sensor – a higher-end flagship perk that's gradually reaching cheaper handsets.
Camera: Mi's lead
Here's where Xiaomi comes ahead. The OnePlus 6T has a very good dual-camera setup with a 16-megapixel main sensor and 20MP secondary one alongside. It comes up short compared to other top snappers like the Huawei Mate 20 Pro and Google Pixel 3 XL, but still delivers strong shots in good lighting and is great for the money.
Xiaomi's Mi 9, as a flagship phone in 2019, opts for three back cameras instead. Quantity isn't everything, of course, but there's very good hardware within. The Mi 9 has a 48MP Sony IMX586 1/2" sensor flanked by a 16MP ultra-wide camera and 12MP telephoto camera. Artificial intelligence uses all three sensors together to put together a stellar shot.
Camera experts DxOMark have already raved about the Mi 9's camera setup, giving it a score of 107 – just one point below the twice-as-expense Samsung Galaxy S10. That's impressive. And in our testing, the main sensor captures quite a bit of detail. The other sensors aren't as powerful, but they're solid indeed. Overall, we think it has a decent edge against the OnePlus 6T.
Verdict: Xiaomi Mi 9
Performance: A year ahead
The OnePlus 6T uses last year's leading Android chip, the Qualcomm Snapdragon 845 – but some months have passed since its release, and now the Mi 9 has the benefit of using this year's chip, the Snapdragon 855.
It delivers more speed in both single-core and multi-core applications, and while the difference isn't obvious in everyday use, you have more power to play with on the Mi 9. Both handsets offer 6GB RAM in the base model, while the OnePlus 6T ranges up to 10GB and the Xiaomi Mi 9 can hit a peak of 12GB.
Verdict: Xiaomi Mi 9
Battery and perks: The OnePlus edge
OnePlus has an advantage here, as its 3,700mAh battery pack is more than 10% larger than the 3,300mAh pack in the Xiaomi Mi 9. The OnePlus 6T is a strong all-day phone that can take a solid beating from games and streaming media, but the Mi 9 is a bit less resistant. On the plus side, the Mi 9 offers wireless charging.
The OnePlus 6T also leads with starting storage, at 128GB with a 256GB model available. The Mi 9 just starts with 64GB, but it also ranges up to 256GB. Neither phone allows microSD cards for expandable storage, which is disappointing.
Looking elsewhere around the phone, we greatly prefer OnePlus' Android skin over what Xiaomi's using, plus the Mi 9's speaker underwhelms.
Verdict: OnePlus 6T
Verdict: Tough to choose
As seen in the showdown above, the £549 Xiaomi Mi 9 has a couple of notable advantages here: its triple-camera setup has a stronger main sensor than the £499 OnePlus 6T, and the Mi 9's newer processor packs more of a punch.
On the other hand, the OnePlus 6T has better battery life, more starting storage, and a better Android skin. And it's £50 cheaper, which is a modest but meaningful difference.
Ultimately, these phones are pretty close, and both are recommended if you're looking for a flagship-quality handset at a much lower price than the Samsungs and Googles of the world. We'd argue that the OnePlus 6T provides the slightly better overall experience, even with the Mi 9's hardware perks, and at the lower price to boot.
Winner: OnePlus 6T