I use SMF for Elliquiy, so... there is that. It scales better than any of the other options, has a better mod selection, better moderation tools and better support.
I've used:
bbPress
phpBB2
phpBB3
vBulletin
SMF
and a bunch of others..
out of them, my favorite would always be phpBB.
For me, it is alot easier to edit and it has a larger database of MODs that I would want. Anything that isn't in the database, I code myself. 🙂
phpBB3 FTW.
IP Board, MyBB, SMF, phpBB by that poll. I personally can't stand phpBB. MODS are a pain to install, and tje community forums seem quite self righteous.
IP. Board will always be better as long as it remains paid. Free software and paid software are as different as chalk and cheese.