I am going to have to agree with some of the people in this thread, and say Wang Liqin is the greatest player ever. His level of dominance from 1998 or so to 2007 was unbelievable. There was a period of 3 years where he and Ma Lin reached the finals of every tournament they went to, with Wang Liqin winning the majority. He had 2 incredibly long periods at number 1, and has won three world championships.
Waldner is good, but I think during the period he was good, the competition level just isn't what it is now. The level of play, level of skill, level of spin has progressed so much, that frankly, its impossible to do the kind of stuff he did when he was younger, because the level of spin in todays professional game just allows so little room for error that you can't execute the kind of stuff he use to do. I think a big reason why people love Waldner is because he is the greatest white player. I mean just look at this thread, there are people voting for Boll as the greatest ever, and yet he hasn't won any world championships or olympics yet. All he has done is win the world cup, which occurs every year. He shouldn't even be in the conversation right now. And yet, because he is currently the best white player right now, he is super popular
Plus the argument that he has lasted throughout the ages, I don't really think should apply, because frankly, the only thing keeping Wang Liqin from doing the same thing is that the Chinese National Team gets new talent so quickly. If WLQ represented any other country he could play for the next decade and still be top notch. Especially when you consider that he probably is in better shape than any other table tennis player. He looks like freaken bruce lee, when he doesn't have a shirt on. And he has maintained that shape for the past decade. He could easily play for another 10 years, and be able to beat most non-Chinese players still.
WLQ is probably also the most athletically gifted table tennis player ever. There is no one with his combination of size and speed. People like Samsonov who have his size and reach look like turtles in comparison. Their movement speed and reaction rate are so much slower. And then people who are faster than WLQ don't have his long reach. So in my opinion, WLQ had an unbelievable combination of talent that made him so good. The Chinese national team has become so good with training methods, that in the future I think the only thing that will make a difference between who becomes the best on the team is born talents. ie, height and arm length etc.