Finding a comparison is very difficult and confusing since everyone uses different tests and arguments.
One such failure of most online tests is that they just test the dead standard default file system, no optimization. For xfs this is a HUGE drawback since by default it is a bit useless.
What would be really nice if someone here volunteered to do a test comparing ext3, reiserfs, reiserfs4, ext4 and xfs. I think those are the mayor contenders on the desktop today. This way we can have an even comparison and tweak the tests as we see fit for everyday use and have real world results in performance.