Also full time Firefox user. Most of my issues are either blocking related so that is on me or apparently sites bugs. At work I use chrome for beyondtrust because I cannot get ff to automatically download and launch rdp sessions. Apparently the content type is wrong in downloaded file so ff will not associate an application with the file so adds several steps to launching rdp sessions. Easier to keep chrome off to the side around for that task.

The other issue is that it does not use Windows ca store for certificates. When company uses internal certificate authority for internal websites this requires users to manually update the browser cert store. Chrome and Edge will use windows ca store on windows. My it dept will not automate this but will manage the windows ca store.