Firefox, because it is so nicely customizable. Of course addons take their toll: the more you have, the more bugs appear. Right now I have >20, which bogs down startup time, but adds a lot of really useful shortcuts, functions, and prettiness. Besides, what's the point of having a fast computer if you never make it do anything? Browsing is probably 70% of the time I spend on my computer, so I think that it's worth making it the best it can be. I could make it minimalist if I wanted that, but I don't. I'd rather have page-load time, bandwidth useage, memory useage, and CPU useage displayed, with my bookmarks and passwords automatically synced with any other computer I use, ads blocked, multilevel tab-bars, image tab scrolling, a download accelerator, easy embedded video downloading, streaming pages, auto URL hyperlinking, easy imdb, google, wikipedia access, and a bookmark and google sensitive address bar.
I don't think any other browser can offer me that, and all things considered the slight unreliability is worth the utility I get from my add ons.
