Urza said:
How about robustness and extensibility?
FF's interface is far more customizable than any of it's competitors, so it unarguably wins there; and it's extensions library pretty much fills in any functionality one could possibly want.
The only front where it's left behind is on performance. However, the differences are meager and if you can get by with such a locked down and limited browser like Opera or Chrome, then I have to think you really aren't using it to it's full potential (eg, stock configuration newbie).
I wouldn't go as far as stock configuration but I do have a minimalist approach. The only extension I use is an alerter for email, Google Wave and RSS. And AdBlock, obviously. I used to have all kinds of shite like flagfox, coloured tabs, twitter add-ons, content grabbers, IRC add-ons, torrent add-ons and lots of other nonsense that I realised was unnecessary so I had a good clear out. I like to keep it simple now.