Especially when I press the volume button, and it shows up rotated 90 degrees at a different side of the screen, or the litany of other iOS bugs..

This experience has stopped being the case for quite some time now. Sure, a 60 USD low-end device is no ground for proper comparison with a 1000 dollar one, but androids in a similar category absolutely have similar animations and "niceties". I have actually recently moved from iOS to Android, and I do prefer the latter's visual UX. I will even go as far and say that there are less UI bugs.

(As for "smoothness", sure, apple's SoC game is far above any android manufacturer's, which helps a lot)