It took me a long time, but finally I decided that Svidler-Topalov was the best game of San Luis. Only then I discovered, that that game was not on the list ...
Initially I was very impressed by Polgar-Kasimjanov, but White spoiled it by missing a straightforward win and making a losing move instead.

@Castlerock:

I had just the opposite response to you; Topalov's play made chess look easy!  Now I know that it isn't, but I played along without a computer and found many of the same moves and even same plans that he did!  Of course, what made him so much better than me was the 10% of the moves that were off-the-chart amazing.   

As for some of the other games, at least one game was drawn without ever leaving known paths.   

I have often read and been told that the real difference between levels of chess is that while the general rules apply in the great majority of games, it's the GM who can spot the exceptional position and make the right choice despite what the rules say. 

Those exceptional positions occurred quite often in this tournament, but the number of moves in any one game that was beyond the ken of most practiced players probably accounted for less than 10%.   

One exception was Polgar-Kasimjanov:  Almost every move that Polgar made was mind boggling.  Kasimjanov made sensible looking moves almost the entire game and still got blown away.   

Well almost.  The resulting endgame was one where an active N and one extra pawn beat down a Bishop.  I felt that I understood what was going on in the endgame at least!   

I still haven't voted, but I'm leaning towards that one win by Polgar as the best game.

Willempie, 

You're right of course.  Svidler-Topalov was a great game.  I could easily have included it, and may remove one of the other games to accomodate it.  I just don't know which one yet!

Wouldn't it be great to have a real book on the order of "Zurich International Chess Tournament 1953" on this tournament ?

Svidler-Kasim A tactical wonderland leading to a maricle draw.
Topalov-Kasim was also a very good game in a totally different way. Topalov exhibited very deep endgame technique.

I chose Polgar-Kasim. It was pure aggression right from the start leading to a double piece sacrifice for initiative & to undermine black's king position.

You dont get to see this type of play too often these days. Morphy, Marshall & Tal would be proud!