Are you direct heating the pot? The heating properties of aluminum are important, then. If you ever think you might go electric, it won't matter as much, and you'll want SS.
1.2 mm stainless isn't that thin....it's an incredibly strong metal. Ever try to drill it?
Stainless will clean easier and look nicer than aluminum, and can take more abuse.
I think it really depends on how much you want to spend. What stores are you looking at? I know instawares.com has good prices.