[pmrphil]

Personally, I like the spray foam. It actually seals the walls to the studs, I don't see a need for a vapor barrier.
I believe there are a few different styles, closed cell, open cell, etc.
I'd do a little homework on the best for your own application.
I wonder if heat/AC type changes anything?
Unfortunately, I think the foam is quite a bit more coin. Location may change that, too.
Good luck.