In short: Anything but Chrome, Edge and Opera.

In long: Firefox beta, Firefox nightly, Firefox, Floorp, Waterfox, Palemoon, Chromium, Ungoogled Chromium, Brave, Some Chromium Fork I can't remember.

Why: FFx: Containers, much more secure than Chrome and Edge, containers, visceral repulsion to Chrome, Edge and Opera, containers.

Why Chromium: Google sabotages Google apps in Ffx.

I have most of these running in front of me now. I'm typing this on Firefox 146.0b9 Remote App running on a Win10IOT VM. Or maybe Win10EDU. One of those.

I use Firefox since it started. At first because I liked it's license. Later because I was in love with the way I'd did things and the add-ons ecosystem it spawned. The first major disagreement came when the search bar merged with the location bar. Then FTP support was disabled. Then RSS bookmarks thingy was removed. Then that stupid hamburger menu appeared. Then features I don't even understand like Pocket appeare. But I continued to use Firefox because the alternatives were worse. Now I keep using Firefox because of apathy and I'm basically the boiled frog of lore.

Brave. Doesn't work with sone video feeds and pop ups but so what?

Firefox, because I can run a real ad blocker on Android and sync to desktop.

I find the compelling reason to use a non-major browser isn't unique features. It's to avoid the harm and exploitation enabled by the two major Chromium browsers, Chrome and Edge.

Firefox. If it weren't for them the entire internet would be controlled by Google and Apple, who have an ad-revenue sharing agreement that perhaps has already influenced ad blocking in their browsers, who keep mobile browsers ten steps behind desktop browsers where they each have a massive financial interest in driving users to apps instead.

I use Firefox almost exclusively, for the continual updates compared to Safari. Apple really wants you to update the OS, and seemingly reluctantly updates Safari separately.

I have used Firefox, Safari and Opera with GhostText, the life-saving extension for text boxes like this one. The associated text editor never loses content, though on a site that allows preview of typing (hint, hint), the editor connection is lost when a preview is had, though that's informal versioning, when you click on its icon again and get another editor page/file FWIW.

Key reason to use Firefox: a plethora of extensions, top of the list, ublock-origin. Other mainstays: cookie deleters, Dark Reader, and nag/paywall busters, plus the wonderful IMSLP delay-killer, the ultimate nag of all nags. Wait 15 seconds (or not!) to watch them beg for money for serving public domain music scores.

Brave. It has its own built-in adblocker that is essentially uBlock Origin equivalent, thus you get a nice proper adblock even past MV3. That being a requirement of mine cuts off most other Chromium forks that don't have a plan after MV2 is culled off the Chromium codebase.

Why not Firefox? I've used Firefox for many years, but I've recently been getting increasing issues with websites (Most notably Cloudflare Turnstile and YouTube) that made me do the jump, at least for now as one can always return.

Brave. Good security defaults and PWA support - just werks

Chrome. I'm the one who still asks to google than to ChatGPT haha

My main browser is and likely will remain Firefox. Despite all the complaints it's the only open source alternative to a major corp controlled browser. It gives the most control.

I have Vivaldi as a second, and distant third Brave, though I avoid using it as much as possible.

Librewolf since Mozilla started ruining Firefox. Brave is out of the question, it's affiliated.

Brave. Good defaults out of the box unlike Firefox where you need to fiddle with bunch of flags.

Cross-platform apps and adblocking.

I use firefox mostly because it's not blink based, and because I've used it all my life, but I also really love the userChrome system even if its hidden behind a flag. Since I use mostly vanilla gnome I use a firefox libadwaita skin [0] that makes it blend in nicely. I used to be jealous of chrome based browsers for their performance but I tried to switch to brave a couple years ago and honestly it doesn't look or feel very nice.

Most chromium-based browsers feel the same and its disappointing. If I wasn't as happy with the gnome skin for firefox I'd probably be using Zen [1] because its nice to see a firefox based browser that tries to introduce new features and create an identity of its own instead of joining a size measuring contest on how hard(ened) they are (I respect them, but it's a very saturated market at this point).

Editing to add that like @WarOnPrivacy said, containers are also a huge feature that I don't think I've seen any chromium-based browsers replicate.

[1]: https://github.com/rafaelmardojai/firefox-gnome-theme [2]: https://zen-browser.app/

LibreWolf