I can't point to a specific article that I feel is evidence enough but there's been a lot of talks and allegations of shady behaviour from Opera lately.
Since it has been forked a while, Vivaldi is a good option. I stopped using it and went back to Firefox but I enjoyed it.
Speaking of Firefox, I've never encountered an extension I used in Chrome (way back) that Firefox didn't have or had a good alternative too. Maybe it's with a look.