I use Firefox mainly but have used Opera in the past too. I think I'll stick with FF because of the number of plug-ins that I have used to get it just how I like it, however there are a few things that I do prefer about Opera, namely its responsiveness (it does seem more responsive than Firefox) and particularly the fact that addresses for links appear beside the cursor rather than in the status bar. I would like to switch Firefox's status bar off permanently but I prefer to see what I'm being linked to before I click it- I've had my fair share of unpleasant surprises at other forums!