I am a live long firefox user that also uses chrome. The difference between the two in term of performance is so small and differenciated between various areas, it doesn't even matter.
Usability is a very subjective topic, but for me there are things in firefox or it's addons that I cannot have in chrome.
And in the end I need to trust my browser for daily (non-developer) use. Trusting google is naive. I don't say Mozilla is deserving of unquestioned trust either, but out of the two it is the better choice.
