I too like a pistol caliber carbine. Fun to shoot, and usually the ammo isn't too high. The Marlin 1894C is my first choice (.357 magnum). It's lite, fast handling, hard hitting with the right ammo, soft recoiling, and just plain good looking.
If you like the tactical look, and who doesn't, the 9mm AR's are a nice way to go. I have a Bushmaster Carbon 15 in 9mm that is a hoot to shoot. It may not have the power of a 5.56mm AR, but it can handle any home defense situation that might actually happen.