The P-38's more complicated logistics requiring larger ground crews and spare parts was definitely a strike against it. However, those citing poor air performance over Europe must explain why that was the plane's fault when it had such a stellar air performance record in the Pacific including cold weather flying over the Northern Pacific from bases in Alaska and the Aleutians.
When discussing which plane was best, a crucial point often left out by P-38 detractors is that initial squadrons of P-38s send to Europe for bomber escort duty were flown by inexperienced pilots who had to tangle with Germany's best combat pilots. The P-51 came along after the cream of Germany's best fighter pilots were dead.
As a fighter over the Pacific, there was a lot less ground fire to contend with.