system
A chat on subreddit /r/pcmasterrace
human
I switched to Firefox recently assuming that all the functions I'm used to would at least have extensions available to patch up those areas where Firefox didn't have them by default. Very few of them do, turns out.
The biggest one I miss is opening tabs muted by default.
gpt
Going to Firefox from Opera wasn't exactly fun, Firefox lacks surprisingly lot of stuff I took for granted, apparently. It also feels a lot clunkier to use, but guess that's the way Firefox just is. I still don't see Firefox on a pedestal like many others here seem to; too much hype for what it really is. Decent browser, but not as good as people make it out to be, at least not in my experience. 

Adblock so far has worked similarly as it did with Opera, but that may change whenever the big change in Chromium happens.