[humanpuff69]

Not actually aware of any bloatware. The UI is pretty much simple and highly customisable. I don't know how simple UI falls under your requirement. They don't update OS but system updates to improve performance with the specs. Running for 1 year and more, my guess is it'll last long. That's what I require.
About custom ROMs, I won't rather go in the risks of breaking system bootloader, rooting the OS and flashing a custom ROM for a more good look which in the end run into incompatibilities with other hardware of the phone. Those stuff from A may look good but I've had problems with custom ROMs before and will rather not prefer them.

but for me despite the heavily modified android which there are some feature that i like in miui . but some of the feature i already get on custom rom or it just doesnt worth the heavyness of the rom . installing custom rom on xiaomi phone is kinda like ressurecting it performance back . i try it on my phone and also my friend phone that have lower ram and before using cusrom my friend phone extremely struggling to do anything and gets hots very quickly but after i install cusrom on my friend phone it worked much better . the heats issue is still there but probably can be fixed with custom kernel or some kind