F4U is a tough one, haven't ran into any F4U pilots that just made me never want to fight them in an F4U again.
There are too many good K4 pilots.
All just my opinion from past experiences or past fights.
F4U, the ones that spring to mind for me are mtnman and I want to say Bighorn, but it might have been another sheep-related callsign that is just refusing to surface in my mind at the moment.
There are plenty of people who beat me, many beat me handily even, but with mtnman and that other guy, I have never felt so thoroughly manhandled as the times I ran into them in an F4U in the MA.
Wiley.