I use both. Most of the time I use the Chrome browser because I'm used to it. It feels easier and faster.
But when I want to be very private I use the Firefox browser. I've read that Firefox does not make money by following where you browse while Chrome may.
I use the Ghostery application on both browsers to see and control who's following me. I've noticed that sometimes when you block a follower a function on my weblog will stop working until I allow it to follow. But at least I'll know about it.