Yeah I used Pale Moon for years also but I seem to remember I had issues with quite a few sites again not rendering but that was a long time ago. Waterfox current is not like the older classic version at all it is way more modern looking and much more responsive. Most sites see it as Firefox and as I said I can't think of any addons it won't take as I use Lastpass, adblock Plus and WOT as well as mouse gestures in Waterfox.
I was an avid IE user until it stopped working properly on so many sites and I like the "File, Edit, View, History, Bookmarks, Tools and Help" toppers like IE had and Mozilla browsers all have that. Chrome and Edge bothers me with the dots for "settings" and then trying to find things I don't use often is just too much work for me. It's personal, no question about it.