infiniteloop wroteyasamoka wroteYou want to swap out a flagship phone for another because the one you have is boring? What does boring even mean? If software has gotten good enough that you no longer need root for most / all of the features you want, is that a bad thing? May wonders never cease...
A phone is a tool. For work, for entertainment, for photography, etc... If it does what you want it to do, then that's all there is to it.
I didn't root for 2 reasons, ctc warranty and lack of interesting roms, by interesting I mean with many mods. Hyperom is said to come very soon, it could finally convince me to root.
The advantage of a Oneplus is that you are free to root and unroot without fear, and you get tons of custom roms. Same goes for the xiaomi
You lose a lot these days when you go for custom ROMs. Off the top of my head:
1) Widevine DRM for protected content like Netflix at 720p and above.
2) Calibrated color profiles (such as Natural mode for Samsung phones which is equivalent to a calibrated sRGB mode). I have yet to see a custom ROM that allows you to clamp the color gamut to something acceptable for everyday browsing (pretty much all content on the web is still sRGB) or photography (your Gallery app is going to show every single image oversaturated). Even if we were to take color gamut out of the picture and focus just on basic grayscale calibration, most ROMs seem to do the adjustments in software and this causes posterization (reduction of the available colors for display).
3) Camera quality, and often quite severely, since you lose the proprietary camera app that comes preinstalled on the phone along with the algorithms it uses for that specific sensor. Computational photography can make or break a phone's camera as evidenced by the use of the same sensor but with successively better software across multiple Pixel generations before the Pixel 6, or OnePlus's often second-fiddle performance even when using the same sensor / sensor class.
4) Stability and reliability. Many ROMs are hit and miss when it comes to that.
The process is nowhere as smooth as, say, installing Windows or Linux on a machine that did not come preinstalled with one or the other.
OnePlus software has been hit and miss since the OnePlus 8 Pro. I had been eyeing OnePlus then 8 Pro display issues happened and the 9 Pro doesn't inspire confidence with all the software issues people are facing. It's just not a device that competes well with the S21 Ultra other than in smoothness and flexibility of custom ROMs, the latter of which is fast becoming a niche use case.
Xiaomi software is improving but is not quite up to the level of OneUI 4 yet.
What do you use custom ROMs for that you're willing to take all the disadvantages that come with having a phone with the ability to install custom ROMs easier?