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 absolutely agree with the 3.5mm headphone port. I use mine all the time as every wireless set of earbuds that I've tried has hurt my ears in minutes. I also can't forget to charge my wired ones. It's getting harder to find a decent phone that has both a headphone port and a micro SD card slot.
I'm currently using a mix of Arch and Fedora, but I've been starting to look in to NixOS.
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.