I'm trying to switch to Firefox but it certainly doesn't feel as snappy as Chrome when doing dev work. I do like some of the tools though. Still undecided.
I've never been a huge extension user (ad blockers and some development tools), so moving to Safari was easy. The big thing I missed was favicons, and those have been in the technology preview for awhile now.
I may explore FF for development, but I'm not sure there is a need since I've already relegated Chrome to a specific task.
I have noticed a few quirks in Safari that I have to work around. Like not rendering things exactly the same way as chrome/firefox. Bit of a pain, but there is never anything that's really "broken".