Pale Moon 25.02
I've had that revision for a week...lol. But I'm glad to see Pale Moon users getting a heads up. It's a fine browser.
Hmmmm - When I tried it, Waterfox seems more like regular Firefox, just as an x64 build. I haven't tried it since Firefox has adopted Australis, so the last time I tried it was back in late 2013 on XP x64 Edition.
I much prefer Pale Moon.
The other issue with Waterfox is that the developer is slow to update. I can understand not wanting to do a new build every time Mozilla fixes some minor bugs and pushes out a new point release, but a while back there was some nasty vulnerability found in SSL, which Mozilla patched quite swiftly, but around 3 weeks later there was still no new Waterfox build. Minor bugs being ignored... No big deal. Major security issues being left unpatched for long periods of time... That's a deal breaker.
Cons would be that because it's using its own identifier (apart from Firefox) to interact with extensions and websites, some users have run into compatibility issues, but these are few and far between. Moonchild, the developer of Pale Moon, uses a Firefox v24/ESR useragent to identify itself to problematic websites. So you're covered.
Pros would be a stable x64 build, and the lack of Australis (it has the pre-v29x Firefox interface)
***I consider the lack of Australis a good thing. If you're a fan of Australis, you'll be left in the cold.
PaleMoon, as Jody more or less covered, is largely for people who don't like the revamped Firefox UI. While I personally wish they'd figure out a way to make more of the page title visible, the rest of the revamp is really not that big a deal. But some people will complain if you move something a single pixel. We used to call them Mac users, but you're starting to find them more and more in other places. As someone who's done some development work, I know there comes a time in any project where it's just faster and easier to chuck a bunch of code rather than try and keep shoehorning new things into it.
But I digress. The two main draws of PaleMoon are that it's 64-bit (which currently means very little, but with WebGL might become a much bigger deal) and it doesn't have the new Firefox interface. Drawbacks would be, in addition to what has already been mentioned, slower updates to fix issues and there's just nothing about a web browser (currently) that needs 64-bit so it's kind of 64-bit for the sake of being 64-bit. You're kind of banking on WebGL not becoming the next VRML (anyone even remember that) or websites becoming so large and complex that the 2GB RAM ceiling placed on 32-bit Windows processes will become an issue any time soon to have any kind of technical justification for it.
Pale Moon is not 64bit. I have PM 25.0.2 and it is x86.