Opera to me is similar to Chrome. They're both extremely nice at what they do, and just in general, yet I'm just too productive with Firefox to switch. I've grown used to Firefox's new tab behavior, having my bookmarks synced, having all the dev tools, etc. While I might be able to (at least eventually) recreate all the functionality in Opera or Chrome, it's just not worth the time or effort. Plus, one complaint I have with Opera is all the crap it has built in, torrent client and all that stuff I don't need or want in a browser.