If you care about performance and compatibility, you prefer Chrome. If you really care about ad blocking, Firefox should be very important to you like a year from now, if Google doesn't retreat before they even lock v2 extensions out. If they back off, what's the reason you have to prefer Firefox?
Two reasons: 1. inertia - I’ve been using it for 17 years and it’s still good enough to not switch, and 2. Google already knows too much about me, I don’t want to give them even more data through their browser. So I guess I do care about privacy…