Invision Power is the same thing. Once bought, you can use it forever. The only nuisance is that you don't have access to the downloads if your support license has expired. I think you still receive security patches through the Admin CP but I'm not sure.

Oh! I must have had it confused with their hosting plans then...

Xenforo

I like Xenforo

MyBB and PHPBB, for the paid ones I prefer vBulletin, haven't really tried Xenforo or IPB.

Only IPB <null.> :3

I think i have decided MyBB as a choice as i have tried phpBB and SMF a lot of times, I also want to give a try to MyBB.Currently I am doing all these in a testing domain, If anyone wants to have a check, they can visit project-samp.ga

SMF is more sexy in some ways. But i would use phBB.

Definitely myBB, simple and easy to use, also has LOADS of features