Theme Support Forum Recommendations

I am looking to create a forum site to use in supporting my WordPress themes.

So far I have looked over bbPress, PunBB, Vanilla and Simple Machines Forum (SMF).

The requirements for the forum software:

  • Easy to use (for admin and users)
  • Easy to theme or style
  • Search capabilities
  • Easily integrates with CMS solution (TXP, WP, etc.)
  • Clean URLs would be a plus

PunBB seems to have a lot of features and I have seen a lot of people I respect using it. I have only tried a demo of SMF, but I have heard some good things about it. Vanilla seems fairly simple. However, I have heard the Vanilla template engine is kind of a pain to work with. I honestly wanted to use bbPress, just because of its ties with WordPress. Can you tell I am frustrated by the rambling?

Has anyone built or used a forum and have any suggestions on which forum software to use? Any opinions or suggestions would be greatly appreciated.