I always want my gallery app to rotate. I never want my email app to rotate. Auto-auto-rotate remembers the last rotation setting for every app I use and will turn it on or off for me. After a day of normal use I literally haven't had to touch the system rotate setting once. It's fully automatic and took zero effort. Having to change the setting manually is more of a hassle than this.
Sleep for Android, great alarm app with many functions.
I have mine set to vibrate my watch for 5 min, if I don't wake my phone will slowly ram up the ring volume. I get two snoozes and then it won't snooze again until I scan a QR code in the bathroom.
Best alarm app ever. It can do a ton.
Google rewards, gives you short surveys for money you can use on the play store. I bought sleep for Android pro a long time ago with the rewards. I have made about 100 dollars. Surveys are easy and fast.
Quick Cursor. Not FOSS, but it is a huge quality of life improvement now that phones screens are getting bigger over time. It displays a virtual joystick which functions similar to a mouse to reach all areas of the screen during one-handed use. This is basically essential for phones with huge screens.
OmWeather from f-droid is ok. Also I just installed Fossify Gallery (photo viewer) and like it so far. I don't know what counts as a QoL app though. Does something like Jami count? It's a more private alternative to Skype and phone calls. I haven't yet tried to use it though.
i heard it was gonna be discontinued (im not sure, cause i can still use it perfectly), but stealth does the same thing and works+looks better than geddit from my experience.
edit: nevermind, i just checked and have got no clue why i thought it was being discontinued.
Reddit started charging per API access, making all the third-party apps infeasible. I know RedReader managed to get an exemption for being particularly useful with screen readers for the vision-impaired. Reddit's API changes still apply; NSFW subs now can't be accessed without logging in, although NSFW posts in SFW subs show fine without log-in.