Most “browsers” being marketed out there are based off of Google’s Chromium project. They are effectively re-skins of it (simplifying a little). Examples include Brave, Vivaldi, Opera I believe.
Firefox is completely separate and independent from this ecosystem (which is also why there’s a separate extension store for Firefox).
The third and last major (>a couple % market share) engine is WebKit, which is the basis of Apple’s Safari.
There’s tons of cool stuff out there, but it’s either niche (platform/use case), unstable to use, and/or both. Examples: Servo, Ladybird, Orion
To sum it up, if you’re a normal, average user:
If you have exclusively Apple devices, probably try Safari (for the synchronization & battery efficiency)
If not, Firefox!
If you need it because of some really messed up development/compatibility issues, the last resort is ungoogled/de-googled Chromium
While on the topic, here’s some cool browser extensions: