I really struggled to switch to anything else. Firefox was definitely the most customizable, but finding extensions to replicate every feature of Opera, and properly at that, was a never-ending nightmare.

Only at that point did I realize how vital a browser has become for everyday tasks, and as a power user, how much you get accustomed to it. Maybe not if you're just running stock Chrome or Firefox with two extensions, but Opera was so feature-rich that I didn't ever install a single extension but needed about a dozen on Firefox to try and mimic it. In the end I just stayed on Opera 12 until it wasn't even funny anymore. It must've been about two years. Eventually so many sites broke that I just switched to Firefox and only installed uBO and greasemonkey. It hurt but over time I just gradually forgot what using opera was like. Sometimes I think back and really miss it. Some of it is just nostalgia by now, but the struggle switching was real.