No other browser comes close to Firefox' array of third-party customizations.

Size and performance

Opera is the anti-Firefox. It's all about features, features, features. That's so Nineties! Opera bristles with bells and whistles most of us are never going to use. That's only part of the reason, though, why it has such a clunky interface. Opera's designers are great at thinking small, but not great at thinking small and smooth. The rough edges are apparent everywhere you look.

Opera's only true advantages are small size and solid performance. But get this: Opera's International edition (which is what came down when I clicked the main download link for Opera 9.02 on the Opera home page) is 6.27MB, while the Windows version of Firefox 2.0 from the main download link is 5.62MB. So much for Opera being teeny-tiny.

Of course, that bloated pig, Internet Explorer 7, tips the scales at 14.78MB. No matter how you slice it, it's pushing three times the download size of Opera or Firefox.