Few weeks ago I posted a thread with Toms Hardware browser benchmarks before Fireforx4 came out. IE9 just came out and was pronounced as the best overall browser across various performance, efficiency and conformance tests.
Now that Firefox4 is out, they were kind enough to re-do the tests.
"If we look at the results by category, Internet Explorer 9 still has the edge. This makes Microsoft's browser the winner by category, as well as by the performance and total placing. There's simply no getting around it, Microsoft Internet Explorer 9 is still the champion."
I personally love using all 3 browsers but I do find Chrome and IE9 slightly better and faster user experience than Firefox 4.