I see a lot of discussion on here about Brave and Waterfox, mainly folks pushing others to use one or the other. Brave never really worked for me in a way that made me want to keep using it until they moved to a Chromium base recently. Figured I would throw up my own observations about each in case anyone was interested in an unbiased look.

TLDR for those with short attention spans: Use either or both since you get Firefox and Chrome without the garbage built into each.

Up front, I will say that I am a pretty basic user who cares about privacy and security more than most but not as much as some of you. As far as add-ons/extension I generally I use uBlock Origin, HTTPS Everywhere, WebRTC disabler, Decentralize, Close Tab Button, a Video Download Helper, Floccus,and a few other things. I host my own NextCloud that holds storage for my bookmarks so I don't sign in to any browser.

Waterfox requires all of those add-ons. Brave doesn't since HTTPS Everywhere, WebRTC disabling, and ad blocking are included. But I really do not like Brave's built-in ad blocking. It allows too much through still and I feel it is probably due to the Brave Rewards stuff. Luckily you can disable just the ad block part and install uBlock Origin. I am sure I could probably get the built in to work like uBlock Origin works for me but I already know uBlock Origin and how to make it work the way I like so I go with what I know. Brave does reportedly have some leaking of WebRTC still on at least some OS (developer confirmed that but i have seen no update if it is fixed) so if you are a little more paranoid you can install a WebRTC blocker there also just to be safe.

My personal add-ons that I like to use (things like Imagus, etc) work on both perfectly fine so there is nothing big to report there. You will find that Brave blocks autoplay by default, so Imagus will not play gif or video on pages that you have not explicitly enabled autoplay for a site.

I also found that the autoplay block caused issues with some sites even after you clicked on a video. This was prevalent on sites like Twitter where a video is embedded in something that pops up when you click it. It was not all of the time though and you can always either allow autoplay on that site or open those up in another browser if it is a problem for you. I usually found that I didn't care enough to open it elsewhere and just did not watch whatever it was at all.

Brave is much faster at HTML5 than Waterfox, although Waterfox seems to be mostly faster overall. I ran some testing on this at test sites and found the numbers I was getting back showed exactly what I thought I was feeling. Always nice to know that you can back up what you feel.

I do have a few sites that work with each of them in different ways. For example, a couple of sites with embedded videos will not work right without AutoPlay enabled in Brave (similar to the Twitter thing above). That is the way those sites are set up (using static images as links to videos for example) and Brave is working as designed there. Not going to hold that against them, I can use another browser if I want to visit them. Waterfox has a few sites that it just doesn't render properly. They work fine in Brave. So I use both and sync bookmarks between them using Floccus.

All in all, Waterfox is still my main browser, but Brave stays installed and right next to it on my taskbar because I want both. A Firefox derivative like Waterfox is great for some sites while others work great in a Chromium derivative like Brave. The only reasons to use a Name Brand browser today are complete lack of technical knowledge (ex: can't use LibreOffice because it looks too different) or a site just flat will not work with anything else (ex: corporate and school sites are notorious for crap like this).

Waterfox Homepage

Brave Homepage

EDIT: One more thing I noticed. By default it seems Waterfox opens a new tab and focuses on it when you middle click. Brave seems to open it in the background. I prefer Brave in that sense.