I agree on containers being Firefox's only headline feature. To potentially add to your comparison list, Brave is the only other fully open-source browser other

I agree on containers being Firefox's only headline feature. To potentially add to your comparison list, Brave is the only other fully open-source browser other than Firefox. I'm an ex-FF user after 19 years of dedication, and now use Edge, but Brave is my close 2nd choice due to its focus on OSS transparency and privacy. And Brave is the only browser that's Chromium-based, fully open-source, and focuses on privacy. If these things interest someone at least.