Johnnie Johnson got hit once only. A reporter asked him why Hartmann, top ace, got 352 kills while Johnson, top Allied ace in Western Europe, only got 39 and Johnson told him that that he hadn't even seen that many enemy aircraft.
This is, ultimately, an impossible question to answer and any thing said on an internet forum is just going to be personal opinions and fanboy pissing contests.
There were many who might be a contender for "the best" and picking one is a fools errand.