I do not know how you might measure this, or if it's even possible, but Vladimir Guerrero had to be the best bad-ball hitter of all time. Here he is putting wood on a 58-foot curveball.
Too bad no video exists of the best Vlad legend: that while coming up through the Expos system, at Double-A Harrisburg, he homered off a pitch after it bounced in the dirt. Maybe it's merely apocryphal. I don't think so, though; I've seen enough actual Guerrero at-bats to believe.