Call me freak, but i actually use a combination of various tools.

First Step: Tag&Rename - can't beat it when it comes to flexibility.

Second Step: Mp3Tag - Check if all files have year, genre and that there is no mixed case in between (like R&B and r&b, since iTunes handles it differently).

Format also the track # and make the text casing to Title Case.

Third Step: iTunes - Here i check if all tags are now alright, correct the ones that might still be not ok.

Fourth Step: Media Monkey - Once again revalidate the tags and use it to build the directory structure.

After this i have a clean and organized mp3 collection. It's a lot of hard work but at the end it looks beautiful in any player.

So at the end they all win ;-)