Key rivals to Firefox are market leader Microsoft's Internet Explorer and Apple Inc's Safari browser.
It doesn't bode well for Opera when they aren't even included in the list. I'm not even an Opera user, but why doesn't Opera get more love? They have some critical flaw in their browser? Or is it just because it's not the default of a major OS?
I do really enjoy that the browser wars got started again because they are now development platforms. Shows that a seemingly dead market doesn't always stay that way if you innovate.