I guess the best proof of what vBulletin can do is here :)
I don't know if i'll need to devellop around this, but this tool is very flexible, with a lot of hacks available and a very good support.
At last, even if it consume too much server resources for my tate, this is a very well coded script.

I can compare with the others as i only know this one, but my vote will surely going to vBulletin.

:D