Firefox: M4 Carbine. You can fit it with a ton of attachments that'll help you get the job done. Chrome: Mini-Uzi. Minimal, small, and fires really darn fast. Internet Explorer: 19th century musket. A long time ago everyone used to use it, but now it's slow and gets fouled up really easily.
Not if you want to hack with cheat engine! Firefox is suckish at speed compared to chrome, and is suckish at simplicity compared to chrome. Firefox is better with add-ons and such, and hacking.
Internet Explorer is a comparatively bumbling browser with it's slowness.
Opera is my favorite, it's extremely fast at rendering pages, and, in the Opera 10 beta, there is a feature called "Opera Turbo," which on weak internet connections, like mine, speeds up site loading by as much as four times faster (it compresses the data, so that less needs to be sent). It's also the most innovative, being the first to have many of the features that are now becoming standard on most browsers. You should check it out, use as many of its features as you can for 2 weeks and see if you like it.