I tend to have to use it at work. The reason I haven't shifted at work is a ridiculous one really - it's the way you can tear off tabs and move them to another screen - it doesn't tear the same way as Chrome. Like I say, ridiculous.
oh, for sure. it's just that at this point in time, on my macos firefox is simply inferior to macos chrome.
fyi i'm a power user (tens/hundreds of tabs, lots of web development etc), so this might not apply to everybody.