I’m a web developer, so I have a lot of experience with all of them. I use Firefox almost exclusively for personal use though. It’s probably the clunkiest resource-wise, but I do love me some plug-ins.
IE in general, is crap. IE8 is a bit better than its predecessors, but historically speaking developers like myself have had to spend hours upon grueling hours going out of their way to make sites look the way they look in every other browser.