I use both. I've been a threads customer since 1998 and vbulletin since 2000.
Each has it strenghts and each has it weakness.
Which software to use is a matter of choice. If you ask here you'll get all pro threads answers. If you ask at vbulletin you'll get all pro vb answers.
Ask your users what they would prefer. Give them a link to a threads site and a vbulletin site and ask them post their likes and dislikes. Just don't give them a link to here or vbulletin. They will be the one using it. To check out the admin sections head to vbulletin. They have an admin demo up. I don't know if Infopop has an admin demo up for threads.
There is a robust hack community for vbulletin and an active template and customization site.
One thing I'd like to point out. Not all vbulletin owners are kids. The more vocal ones are kids, but rest assured there are many old guys like me that own vbulletins. They just choose to stay quite.
