Polyeurathane(sp) I've heard, is supposed to be the toughest paint, as far as scratch, and chip resistant, and longevity. Many body shops don't like to work with this in their shop though fumes from it can cause havic with the fresh acrylic (base/clear) on other jobs in the shop.

As far as corrosion(ie; rust?)? I think the prep of the body is probably the most important part to prevent this problem. Old rust cut out and replaced with new steel. Proper sealing of inner panels, ie wax-oil. etc.
There are several good two-part epoxy primers that seal the surface better than standard primers. This properly applied to a good surface will play a big part in preventing rust, from chips etc.

IF you meant "paint oxidization" but used the word corrosion, I think most of the good quality base/clears will resist this problem for many years if properly maintained. (ie; washed, waxed regularly) Straight enamel paints are probably the least resistant to oxidization. Forget the water based paints (my opinion).