"It is all what you're used to"
I don't think this is true.
Ubuntu is far less consistent with keyboard shortcuts and menu bars from app to app (OSX has this nailed). This is overwhelming my biggest problem. cmd+c, cmd+v for copy and paste across all apps. Not all apps minus terminal. Double click URL portion in firefox, entire url is highlighted, double click url part in other places, only that word/segment is highlight (I guess it's this 8 year old bug? https://bugzilla.mozilla.org/show_bug.cgi?id=611162)
Sublime sometimes opens with the menu shown, sometimes with it hidden (I've tried to script this, doesn't always work). Sometimes the window shows up minimized (scripting this catch 90% of the cases)
On quit, Firefox always restores the DDG and Amazon search options, but not the other ones. Why can't it remember this? (there are other cases of partial configuration amnesia for various apps)
"Ubuntu Software" doesn't list available updates for installed "Add-ons", you have to remove and and re-add when you know one exists. It also doesn't let you "search" installed even if you're on the installed tab.
When my I wake my screen up, there's a brief flash of my unlocked screen (someone could theoretically take a picture) before the lock screen comes up.
In OSX and android I just enter my carriers free wifi settings and it works. In Ubuntu, I'm given a bunch of detailed options, and I've yet to find the magical combination that works.
While on battery, the time remaining can be comically off when waking from sleep (23 hours, really?!). I've also had it say 10 minutes left when it shut down.
There are plenty of apps on extensions.gnome.org (available in "Ubuntu Software") that constantly crash gnome. Go through systemd logs, find which ones are causing the problem, try to fix or uninstall.
The list goes on and on. Correct battery time, configurations that stick, consistency from app to app are polish, not preferences.