I usually go for any less-sweet, starchier variety, depending on what's at the store. They tend to hold up better in baking and are usually better balanced with the added sugar than the sweet varieties. Hope that helps!
Granny Smith and Macintosh combine to make the perfect pie or crisp filling because macs break down to provide that sweet sauciness while grannies stay firm and provide that tart counterpart. I think Cortlands and galas are also great all-purpose baking apples.