I use Firefox because I can use the full version of UBlock Origin, and UBlock Origin also works on the mobile browser.
I also make heavy use of the extension Multi-Account Containers for signing in with different accounts for the same service at once.
Lastly, I prefer the UI for Firefox over anything else.
I've seen a website that silently truncated my password during a password reset, but then wouldn't truncate it during login. It took me a while to figure out why my password never worked.