My default browser is firefox and sometimes i use chrome and rarely i use opera. Firefox is slower and buggier than chrome, it memory leaks, flash is buggy and crashes and slower, clearly inferior to chrome, search is slower.
The only reason i stay with firefox is all my crap is on there, it doesnt log every piece of data as far as im aware like chrome does. I also have used all the browsers on android and firefox is fine for me on it. I use an ipad and use only safari, its pretty decent, i wouldnt install chrome on it despite safari not allowing you to block googles ads outside of chrome.
This is mostly because chrome tracks everything, and i think there should be competition. However yahoo jumping over to firefox instead of google search is backwards for firefox. Firefox wants more users, not less, and its just another reason for average user not to use firefox. Not everyone wants to piss around in the settings to change it. Its a huge fail. Firefox needs to add google chrome style predictive search bar, speed up their flash/html5 if possible, and they would be getting closer to being level with chrome, and of course not using yahoo search.