As a Chicagoan, I have a few reservations about anyone with the last name of Grossman winning anything (Gene Grossman in this case). So, Grossman and Helpman are out of it.
Let's put my money on Jean Tirole, because I like French Toast, French dudes, and I/O Psychology.
Update: Foiled again, damn it! These guys weren't on the short list of potential Nobel Economists anywhere. Which...of course begs...if economists can't predict who is the best and deserving among them, what chance do they ever have of forecasting/predicting any kind of change in the economy?