[BrianG]

I tend to like the "hammered finish" paint on Aluminum. It is semi-glossy and creates a texture to hide many minor imperfections. See my BL Conversion link in my sig to see the results.

It does chip off eventually, but so will any paint.

I use regular flat paint as a primer (regular primer doesn't stick as well for some reason), and then only a light coat of the hammered paint is needed. Otherwise, you see the Al through the little pinholes the hammered paint creates and you'd need multiple coats.