I'd say the Tempest. 4x20mms and 2 1,000lb bombs give it significant air-to-ground punch. Unlike the P-40D, this aircraft is an uber-fighter, too. Yes, the P-40 carries a bit more ordnance. It doesn't have the four 20s, though. Drop your bombs and the Tempest is the most lethal prop aircraft in the game. Honorable mention goes to the F4U-4. Two 1,000lb bombs and weight rockets. It, too, is an awesome fighter but it lacks the 20s.