I currently run a phpBB...hasn't given me any problems, but I'm intrigued by IBF.
So, with out the "just try them out yourself" comments...can you tell me why you chose phpBB or chose IBF. What stood out that made you switch from what you used to use? What is your favorite feature about the forum you use?
Which is easier to use? Which looks better? Yadda yadda yadda.