Chrome, because nothing else seems to do as much as it does but still get out of the way of the content it contains. Plus, it's convenient having shared history between my mobile and desktop.
Google Chrome all of the way. I used to use Maxthon however the interface and speed is slightly annoying (it takes a tad longer to load pages, and appears to render them in a fashion that is very similar to how IE/Opera does it).
It seems like this thread pops up every couple months, always a new thread and usually by a different user. Anyway, I use Chrome for most things. I do use Firefox, IE and Safari to test cross-browser compatibility when it comes to Web design, though.
Firefox, because it has very useful add-ons, plus nice features, and the loading speed of webpages is quicker. I like how you can pick a background too. 🙂