As a long-time user of Pentadactyl, Firefox, and vim, I'd like to make the heretical suggestion to try w3m in emacs.
Having a web browser fully integrated in to a powerful editor like that is fantastic. It's far more powerful than what you'd get from the Pentadactyl/Firefox combination, with the disadvantage that w3m can't handle Javascript.[1]
w3m's also far faster and a lot less bloated than Firefox. For sites that work without Javascript and where I only care about getting information in text format (which is probalby 99% of the sites I use), it's just about perfect for me. For the rest, I have Firefox, Opera, and Chromium as backups.
[1] This is not a big loss on most sites, as they can usually be used just fine without it. In fact, it's often good to have Javascript turned off so as to avoid Javascript exploits, tracking and advertising.