It IS an opinion, so no there isn't. Everybody can say something different. You would have to say something like "So and so, is the best rider as far as number of tricks people can do." Or "Blah blah is the best rider as far as going big." If you just want to say something like a person is the best rider the whole scooter community would have to make a complicated rating system involving style which can't be measured, smoothness which can't be measured, number of tricks, and things like that which wouldn't really be fair to some people. It can't be said and be a fact.