Isn't there one that starts with a V that is non chromium? I can't stand Firefox and being chromium is like being Linux it doesn't mean that all Chromium browsers are the same.
And, realistically, it's either one of the Chromium-based browsers or Firefox-based browsers under Windows.
You can install the ancient and unsupported version of Safari under Windows, but that's of very limited utility in my opinion.
I am glad to see that Mozilla Firefox has remained a power player in the web browser space. As someone who works with screen readers and accessibility issues, you often need to jump to/from Firefox to/from a Chromium-based browser whenever some web page, for some unknown reason, simply doesn't play well with one of the other. Were only Chromium-based options to exist, many dead ends that needn't be so would exist.
There are many "fully compliant" web browsers that are cross platform, not based on Chrome/Chromium, are privacy focused, light on resources and fast. Just because they are relatively unknown doesn't make them less capable of protecting your data/privacy.
Librewolf, (number 1 privacy focused browser on https://privacytests.org/),
Then there's Pale Moon, Netsurf, Dillo, Firefox, Waterfox, Tor, Basilisk, Floorp, QuteBrowser etc.
There other fully standards compliant, non-Chrome/Chromium choices that use WebKit like Midori, Sleipnir, Orion etc. All perfectly capable browsers with small user bases.
I have been running Chrome for maybe 17 years... and was going to switch to Edge (also Chromium) because other than Google Chrome it is the only one with a major company supporting it. I DO use Opera a bit but only because it has VPN without login (yes Edge has VPN now).
What triggered consideration of change was the deprecation of Manifest v2 breaking μBlock Origin ... Yes, I know there is a Lite version. Right now the v3 Lite version of Origin is working okay because it is blocking the ads for Disney+, so I am delaying the change.
That said, I am very well aware Brave is more security conscious and that Firefox is in a different ecosystem.