Gerd Barkhorn did better, however keep in mind that these German pilots flew combat years before WWII started. (I.E. Spanish war ect....)
Hartmann is the all-time Ace of Aces. His combat career did NOT begin in Spain. He did’t begin flying combat until 1943.
As to the best fighter? All around? The P-47 hands down. It broke the back of the Luftwaffe before the P-51 came in with the broom and dustpan. It had the speed and firepower to be an effective air to air fighter and of course it excelled at low level work with its ability to haul ordnance. One thing that people forget about the P-47 is that with its turbo-supercharger it performed much better at high altitude where the bombers flew. This allowed it to maneuver with the best of the German fighters and it’s roll rate was phenomenal, almost, if not as good, as the FW-190. Most importantly, the Jug brought pilots home, often with valuable lessons learned.