I'm looking to start a new forum, and I have no idea where to start. I thought vBulletin was the best choice, but then I wondered if it's worth it for the extra money.
I would recommend Vbulletin. It really is the best.
It's because most forums i've been on use the format so it's very accessible and people know how to use it. There's a reason most of the internet forums use it.
If you get a good site going, then move to vBulletin. But paying $/£250 for the files isn't worth it for a new forum, neither is getting a cracked copy of it.