The short answer is depends of what version you have on the kits. If they are all the Gold Edition versions they are pretty easy builds of the 4 listed I would say the Spitfire and the Mustang are the easiest fliers of the bunch but they do present a few challenges on take off and landings. The Gold Editions were modified to improve flight characteristics. Some of the old red, blue, yellow boxes can be real nightmares to fly. Give us a few more details if you can.
Mike