IMO, the best user is Archived Post, he's been very active!
He is very active, but i wouldn't say they are the "best user".
They have a very bad tendancy to talk to themself hours/days/weeks/years on end, and no one else can get a word in edge wise.
They also had a tendacy to argue with themself, and lose the arguement...
If it wasn't for the forum change, they would still be talking to themselves.
I've not ben here long enough to understand to whom is truly Useful, however, Some are truly way more intertainment! I'll vote though for the user with the live long and prosper handle. Allthough I just saw someone with like 90+ posts. in two days? thats allott of things too say.
Wish I could think of something wise and cool, and all That!