In trying to rank my 5 favorites (somewhat of an impossible task), I'd go with...
1. Blueberry
For me, a luscious blueberry pie is what apple pie is supposed to be - a fail safe all American staple.
2. Lemon
I adore lemon pie. Curiously, though I can enjoy them with meringue, I actually prefer a "flat top" on my lemon pie.
3. Chocolate
I think chocolate pies are underrated. They usually don't top many favorites lists yet just one slice can be the decadent highlight of your day.

4. Cherry
Cherry pie is a little ways down the list just because it can be a bit fickle.
5. Banana Creme
I like it but a little goes a long way.
Pies that don't float my boat (despite their popularity)...
Apple
Pumpkin
Strawberry
Jeff