What is Your Favorite Forum Software?

What forum software do you guys like, and explain why.

Forum Software:

• MyBB
  
• IP.Board
  
• vBulletin
  
• Xenforo
  
• Other
  

My Favorite:

MyBB - I like MyBB because it is easy to use, easily customizable, vast variety of plugins, and the best part, it is FREE!

I have used all the ones you mentioned and SMF, but I keep coming back to MyBB - probably due to its customisability.

SMF was never my favorite because it takes forever to reply to a topic and it pisses me off lol