Here's an article from the hoopsworld arguing that Shaq's career is way above Duncan's.

Gutierrez: Shaq's Career Still Outshines Duncan's | HOOPSWORLD.com | NBA News and Information | powered by Basketball News Services

As far as I am concerned, Duncan's still in his prime. He can win more and produce more. Shaq looks to be nearly done.

The author is a Miami beat writer and Heat slappy of the nth degree.

I seem to recall Shaq losing two Finals series.

Per 48 playoff minutes in Head to Head matchups, Duncan has outscored Shaq 29.2 to 29.0 points.

But since Duncan is 4 years younger, I would definitely give him an edge when it comes to total playoff success.

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Momma was queen of the mambo, Poppa was king of the congo, deep down in the jungle, I start banging my first bongo
Every monkey like to be, in my place instead of me, cause I'm the king of bongo baby, I'm the king of bongo bong
-Manu Chao

Duncan has it all. He is a quiet competitor, ultra talented and a total team player with next to no ego for a superstar of his caliber. He just gets stuff done without all the commotion. I wish we had a player like him to build around.

I'll say equal.
Shaq has the personality and charisma. Both were good in there own ways so I'll give Shaq his only half a vote...

Yeah, but Shaq brings the "intangibles" like Kazaam...

Shaq has had a greater impact on the game. The rules have been changed to allow him to shove, shuffle and bull his way to the basket.

Duncan relies just on talent(big deal) and hasn't had the rules changed for him and he doesn't even have a good personality or make movies. Anybody can do that.

I give the nod to Shaq.

yeah, but DOB cannot be a determining factor.

You also have to consider their teamates, because they help them. But of course, that doesnt help because they only get it at the post and do their tactics.

Right Now Shaq

But Duncan will outshine him, he will have better late years than Shaq. Thats the deciding factor.