Still trying to eke as much life out of Internet Explorer. One major plus being just that it's no longer being developed for a long time so doesn't change (in terms of features), but still gets security updates. Sadly, after GOG became the first site I use that stopped supporting it a year ago, I have recently noticed a few others, albeit stuff I rarely end up on and can do without, and for some time now there's a notification at the top on Facebook saying it will no longer be supported soon, so that will be a problem.
Secondary browser WAS Firefox before Quantum, but I stopped using that completely then and there and Vivaldi moved from something of an experiment to secondary (and only for GOG, for obvious reasons), and I guess soon enough it will need to move more and more to primary. And it does check many of the right boxes, but being based on Chromium is a major red flag, plus that for example it lacks something as basic as a working popup blocker (there's a setting, but seems to be a Chromium feature that's not properly supported, turn it on and has no effect, and support said they can't help with that), and has big problems with major security software, or those have with it, for example I see from experience that ESET causes it to very frequently stop loading pages and if you close it after that happens without closing all those incompletely loaded pages and trying to open a blank or local one it will no longer start at all, and Bitdefender blocks it completely (and silently, not even a notification) from starting unless you add it to advanced threat defense exceptions (of course, this at least is easily solvable, the ESET issue didn't seem to be when I tested).
