mrkgnao: P.S. You use IE? Less than 1% of MaGog's users use IE. Just saying.
Pidgeot: Firefox has always seemed like too much of a resource hog for me, and Chrome's lack of a real menu bar is an instant turn-off. That really only leaves IE.
Even that has not always been easy; I had to skip IE9 because the forced ClearType gave me headaches. Even the current grayscale antialiasing from IE10+ isn't all that great to me, but at least I can bear to use it.
If not for the security improvements and support for these shiny features that don't actually add anything valuable, but which every web developer *insists* on requiring (with no graceful degradation for non-supporting browsers), I'd still use IE8.
I am well aware I am in a minority opinion here.
In my case, it's not usually the fancy features (I'm using polyfills for those anyway, so NoScript won't break them but old IE can still have them too) but, rather, the bugs. It's a major pain to support IE when every other browser follows the spec and tons of IE users are still back on a version that does something like interpreting box sizing wrong causing word-wrap to wreak merry havok with floated elements.
(Because proper solutions like, for example, the flexbox layout model are even less backward compatible)
As for Firefox, I'm really looking forward to their e10s/electrolysis project to make it multi-process like Chrome for the following reasons:
1. Thanks to the effort to repurpose as much as possible for use on weak smartphones via Firefox OS, Firefox is actually very lightweight these days and one of the goals of e10s is to use shared memory heavily to retain that lightness.
2. Firefox's bad UI performance is because you have everything in one cooperatively-multitasked mess like Windows 3.1.
3. Firefox is pared down enough that you need extensions (often bloated or buggy) to make it useful... e10s will finally enable a Chrome-style process manager which will make it clear which extension author you should be yelling at to get things fixed.
(e10s is taking forever because they need to write all sorts of compatibility shimming and do community evangelism so the extension ecosystem doesn't break in the process. Basically, the same reason Windows is such a hacky mess internally but has decades worth of backwards compatibility.)