Throw my .02 in here right quick.
Shadows of the Empire and Rogue Leader (and some parts of Rebel Strike - seemed to try to get back to the SotE feel)
But if I had to pick just one, then Rogue Leader. If you're unfamiliar, Rogue Squadron took one of the best parts of SotE and expanded it into a whole game. Then, RL, the sequel to RS improved upon a great arcade-y game.
- Berban