My favorite would have to be Volkner. He, if I recall correctly, was the only Gym Leader who really didn't want to battle. Also, Flint's concern for him showed that the Elite do take part in the small affairs of the little people.
Two things that also helped: He had an Ambipom. He's also handsome.
Volkner's really the only Gym Leader that I like enough to mention, though Morty is a close second.