I can't vouch for which is the "best,"since that opinion is extremely objective (subjective? someone help me out here??), but my personal favorite fighter of WWII is the BF-109, either the F or G series. It was simply a jack-of-all-trades; it wasn't extremely fast like the Mustang or Lightning, it couldn't turn extremely tightly like the Spit or Hurricane, it didn't have the firepower of the Focke-Wulf, etc., but it did every one of those at least competently. Most other fighters had a certain tactic to use, be it strictly BnZ (FW, Lightning), TnB (Spit), or others. It could adapt to almost any situation and come out victorious, if the pilot was competent enough. I think (and this is JUST an opinion) that if the Germans weren't so heavily outnumbered from '43 onward, the air war would have favored the Germans by a much bigger margin.
Anyway, that's my $.02. Cheers!!
"A thousand flights mean a thousand landings. Somehow you always have to come down, one way or another. And then one day it will be for the last time."