ExtremeTech has written up the most comprehensive comparison between recent versions of three browsers that I've seen.
Now, in case you're wondering - 'oh yeah, you are blogging this because IE7 comes up top, right?', I'm not, because that is not the article's conclusion.
In fact, the article's conclusion is not conclusive in this respect, but the review team did conclude that IE7 (beta 3), Firefox 2 (beta 1) and Opera 9 are all pretty good...
"Users will reap some benefits from upgrading to any of these browsers, and all are excellently engineered, well-working software with lots of convenience, capability, and security."
The review (it's worth a read) has plenty of detailed feature comparisons and summaries on the 'best of / worst of' on each of the browsers (see summaries on Opera 9, IE 7 Beta 3 & Firefox 2 beta 1) and performance comparisons on each.
My personal take is that the IE team has done a really great job over the last year or so getting the IE team up to par in the browser space. Getting this kind of positive review (from a tech-savvy site) for a Microsoft browser would have been unimaginable a while ago.