I don't think many JFBs are very happy with the Ki 44-2c. Apparently the 40mm guns never hit anything. Pretty much reflects how they worked in real life.
You are sort of stuck with a delimma (as well you should be). In game terms the tojo is the best fighter in the game from mid 42 to mid 43 and you should build plenty. However, any 2nd generation Allied fighter will tear it up. Problem is that even later versions just don't go fast enough and speed seems to be the key asset for a fighter in AE.
Then you have the Frank which is much faster but can not climb very well. In air to air combat it does much better vs Allied fighters but is still slower than most. However, you have to deal with the pitiful service rating. As EUbanana states a plane like the P38 is very useful in certain roles (sweeps and long range escort) but It would be a sad situation if all of my Allied fighters were P38s. Franks are the clear better plane but I suspect that a lot of them will die on the ground.
One last thing in favor of the Frank. As an Allied player, I won't hesitate to fly my heavy bombers into any number of tojos. But Franks, Georges, Tonys, Jacks and such can shoot down big bombers, and that is important.
the time when lots of aircraft die on the ground has passed when radar was fixed with the latest official patch. No matter which service rate, I have hardly destroyed any fighters on the ground because they all get airborne. If they fail to get airborne then it´s a "player fault" because they were at a base without radar. With radar, you have to all damage them before they are sitting on the ground.