Right now it would have to be Jack. I mean take a look at his 18 majors. And he finished second how many times again.... 10... 15...???!??! Don't get me wrong Tiger will eventually be the best to ever play the game, but if you are talking about who is the greatest player the game has ever seen RIGHT NOW, it would have to be Jack.
Maybe in 3 years after this discussion re-opens it will be Tiger because he will have broken Jack's 18 major mark. Isn't that what they always say as well... A golfers greatness is determined by the amount of majors he's won??
Right now its Jack
2-4 years from now, now doubt about it: TIGER