I used to use Brave, then used Bromite but that got abandoned. I think there's another fork of it, but ultimately I just use Firefox which has worked better for me overall.
Browsers are a big attack vector for exploits and security is very important. Firefox releases patches regularly and I don't have to worry about it being abandoned like some others. I disabled whatever telemetry / sponsored stuff they have enabled by default and feel it's a good balance of security & privacy + doesn't have the DRM crap chromium is trying to add.
Their extension support is nice too.
Yes, you should support open source when possible if the project(s) you use are beneficial to you! Your dollars are far more valuable to help out a small team of independent volunteers vs multi-billion dollar corporations that really don't need it.
If you can't donate money, donate your time / skills or do both! Make the world of software a better place, one small contribution at a time!