Err... I think Brads hosting company has been around for alot longer than Jupiter.
No idea whos is "better", but this isn't really about that.
sinhost.com
Created: 18-feb-2000
I think GFY is GFY for a bunch of reasons.
#1 because they have an awesome brand name for the occassion
#2 probably being because they were the first big threaded forum success on the scene & therefor they have the largest searchable post archive.
Somewhere you can factor in the promos, drama & the fact that so many new people manage to find this place daily.
I see a lot of forums these days offering $$ per post... but imo, that isn't what makes a good forum.
You gotta work it ;)
Anyway for those that really care about this stuff... someone did an interview with Lensman awhile back and they were talking aobut the success of GFY.