I think Batman is smarter and a better speaker so on the surface it would seem Batman would win the debate. That being said, I think Batman is a man on the edge. Punisher could probably point out how many innocent lives have been lost as a result of The Joker alone. Add in all of Batmans other psycho rogues gallery and you are looking at thousands of innocent deaths that could have been prevented by taking the criminals life. In the end I think batman would see Franks side easier than Frank would see his.