A number of people picked Wildcats. I suspect Promethea didn't get picked because it's already in Absolute form and there's supposed to be a sort of omnibus edition coming out one day.
While I would definitely buy a Tom Strong omnibus, I don't think it was one of the more popular ABC series, so the voters might not have really been aware of it.
"You don't ever quit. Not even to your last drop of blood. You got folks relyin' on you then you just can't afford to." Sean Noonan-Hitman #47