It might be a snoozer, but the Galaxy S25 Ultra reigns supreme in terms of sales. Sorry, Vivo, Oppo, and Xiaomi!
This year might as well be the year of the «Ultra» phone, given how great and exciting Android phones with the respectable «Ultra» suffix have been released in 2025. 
We got the Galaxy S25 Ultra, the Vivo X200 Ultra, the Xiaomi 15 Ultra, and the Oppo Find X8 Ultra. What a respectable selection of heavy-hitters indeed! I’ve used or at least played around with each one of those phones, and all these phones are definitely up for contention for the «best phone of the year» title. 
Yes, even with the Pixel 10 and iPhone 17 series unreleased, it’s doubtful any of them would be able to match the Ultra phones, methinks.
One of these phones is arguably the most mundane and boring, and that’s certainly the Galaxy S25 Ultra. It has a great camera, but the Xiaomi 15 Ultra, the Vivo X200 Ultra, and the Oppo Find X8 Ultra certainly beat it in terms of hardware. 
Many of these phones have exceptional 1-inch main camera sensors, which certainly matters when it comes to raw optical image quality.