Ubuntu LTS. I chose it because it mostly just works and there's plenty of documentation and q&a online (StackOverflow)
As for the problems, on the desktop side I wish it was more polished. For some reason every time there's a wireless printer in the network it tries to reinstall it (fix: sudo systemctl disable cups-browsed), error reporting is annoying (fix: sudo systemctl disable apport), can't easily set full RGB out on HDMI (fix: xrandr --output HDMI-1 --set "Broadcast RGB" "Full"), volume change is laggy on some soundcards (fix: enable-deferred-volume = no) and small quirks like this.
The only quirk I haven’t been able to fix running Ubuntu as my main work OS is the scroll wheel on my MS mouse jumps pages instead of smoothly scrolling. I’ve tried many recommended fixes to no avail over the last two years (on my phone away from my work laptop right now so I can’t check my notes on what I’ve done otherwise I’d post them here)
As for the problems, on the desktop side I wish it was more polished. For some reason every time there's a wireless printer in the network it tries to reinstall it (fix: sudo systemctl disable cups-browsed), error reporting is annoying (fix: sudo systemctl disable apport), can't easily set full RGB out on HDMI (fix: xrandr --output HDMI-1 --set "Broadcast RGB" "Full"), volume change is laggy on some soundcards (fix: enable-deferred-volume = no) and small quirks like this.