IE.
I've thought of jumping ship to something else but it seems like everything gets roughly the same amount of positive and negative feedback from people. So I haven't been too convinced to bother. All I know is fuck anything from Apple. They always try to sneak extra shit onto your pc.. I also don't know how trustworthy Google's Chrome is.
As for IE vs Firefox, I've heard a lot of back and forth for both. However, as previously warned, Firefox takes up more byte space, which is currently an issue with me, until I can get another hard drive. It's that tight.