I have always been a heavy user of Firefox, even in the pre-Quantum days.
My main reason was that Chrome would sync my bookmarks out of order and I am a heavy bookmarks sync user.
I gave Chrome multiple tries for bookmark syncing and yet they would sync them out of order (can't believe I am the only heavy bookmark user on Chrome who cares) so I just stuck with FF.
Then the privacy concerns happened and I stopped trying Chrome. Then Quantum happened and now FF is the lighter, faster browser. I had no real reason to use Chrome except browser compatibility and a few dev tools.
Then ublock origins is getting blocked and now I am recommending people to switch to Firefox.
I do like the seamless and easy to use multiple profiles that Chrome has. Makes it very nice to isolate your tasks. If I am not logged into reddit or HN I waste less time and less cognitive overhead. FF technically has them but I hate how I have to open a prelaunch dialog to use them.