I'd get Real Racing before the sale's done. You can always buy Modern Combat at a later point (and an added bonus would be a possible price drop =D). 'Course, it also depends on what genre interests you more.
No real iphone gamer should go without any of these 2 games, so you really should get them both. But if you wanna know whicdh to get first I personally would give the edge to Real Racing, its a very cool gaming experience. YOu must get Modern Combat though, best FPS on the idevice so far. You shouldn't torture yourself with these "which one" threads when it comes to 2 games like this. Just drive to the store and grab a $15 card and get em both.
Get whatever game you are interested more in. If you like racing, get Real Racing; if you like first person shooters, get Modern Combat. Personally, and I'm a fan of both genres, I like Real Racing more.
