Well in all fairness,
I think it's better with user created fighters because one will not complain about having a fighter with less stats than the other.
Then again people don't have the same preference between wrestling, jiu jitsu, kick boxing, etc, etc. So yes, styles will make fights.
IMO, we will all create our perfect fighter and it will correspond better than the actual roster.
OFC I would want to pick Anderson Silva in MW and own everyone, but again it would be a little unfair for those who have a fighter with stats of 80 ;p