Wimbledon has a great tradition but let's face it , the style of playing does not make for great watching. In terms of entertainment (as a fan) the US Open is the most fun.
As someone who likes and enjoys long exchanges, Roland Garros and Flushing Meadows are riveting stuff. Tv wise also the US Open is frendlier with the evening session for us North-Americans.
Howevr if i were a player on my top list it would be Wimbledon followed by Roland-Garros, afterwards it would be the US Open.