Re: Firefox really is the worst
I must really have been using an old version. Had to upgrade 4 times to bring ff to current level 58. Sad to see one of my favourite add-ons "Faviconize Tab" (allowed each tab to be thin down to the width of a favicon) gone. FF 58 "kindly" allows you to list legacy add-ons no longer supported, then "helpfully" suggests that you may search for replacements, but when you press the button, it's just a dumb old list of all add-ons.
To be even-handed in criticism, Opera hasn't had its most distinctive and useful feature since Opera 12 (2011?). The feature was "Create Follower Tab". This opened a new, initially blank tab. Whenever you clicked in the current tab, it displayed the content in the Follower Tab, and the current tab stayed loaded. Usually way more handy than the now ubiquitous "Open Link in New Tab". Even then it was buggy to the extent that it didn't remember Follower Tabs between sessions. In the new session, the Follower Tab became a tab like any other. I like to say that "It ain't Opera until it has Follower Tabs". Vivaldi also doesn't have it.
I use Opera developer, Vivaldi, Firefox, simultaneously (24GB RAM helps) with lots of tabs open. Certain sites work better with one than with an other. Multiple accounts at the same site, easy this way instead of logging out and in. I use Sleipnir a bit. Otter rarely. Installed Pale Moon recently, but lightly used. Uninstalled Chrome years ago as hopeless. It must have improved a lot for people to be using it in 2018. My Security Prime Directive is never to use MS products in Windows unless absolutely necessary, because "undocumented features"; so no Edge, and no IE for decades. Guilty secret: I use Process Explorer. Lame excuse: it isn't "really" an MS product. Finally, Lynx. Sorry, it's difficult to get back to a text-only interface. But it's been used in the last couple of years, for sites blushed by the deepest scepticism, but profoundly wanting to be read.
Sorry, there isn't an icon for "Prepare for boring, me young buckaroos."