Flatness
Flatness counts a lot in my book.
Keltec P32 wins here, P3AT is next.
I have an American Arms Escort .380 that is very flat, perhaps more so than the P3AT, but it's a bit longer and it's all SS.
Don't overlook the NAA Black Widow. Much thinner than a P32, except for the cylinder. .22magnum is probably better than .32 ACP, but I don't have the numbers handy.