Some Facts
World cups : ZJK reached finals two times, won it at his second attempt. Ma long failed two times in the semi finals, facing inferior opponents (samsonov & boll) and lost. He clinched the world cup without ZJK attending @ 2012
World championships : Ma long failed twice facing wang hao, a player who is consistent yes,but for ma long fans "no match for him". ZJK beat wang hao in his first attempt.
I dont take olympics into consideration because ma long was out due to his injury that caused him to fall in the ranking list.
What I am trying to say here is that, what makes a player great doesnt have to do with how staggering table tennis he can play, but if he can cope with situations under immense pressure. And ZJK proved he can do that.If they meet in the final @ wttc 2013 and even if ma long wins, it wont be an "easy win" as many ma long fans claim
Besides, ma long had more opportunities than ZJK to prove himself and he failed. Im not making a comparison about who is better here, dont get me wrong please
In the end if ma long manages to cope with pressure, then he will be greater than ZJK eventually.
But that is only a theoretical assumption, he must prove it on the court.