F4U-4.
That should really say it all, but since you're likely to ask:
The F4U-4 takes all the good points of the Corsairs and improves on all of them.
She's one of the fastest props at all altitudes, with only a handful that will run her down, and even then the difference in speed is rarely significant. Acceleration is among the top ten. She won't out-sprint the La-7, Tempest or Spixteen, but the difference is only within a second or two.
Rate of climb is above average and certainly better than the 1-series F4Us. However while a number of fighters (Spit XVI and 109K particularly) may still catch her over an extended straight climb, VERY few aircraft will catch ANY Hog in a zoom climb, which the extra power in the -4 makes even more remarkable. Energy retention is among the best, and judging the E state of the Corsair is difficult. A Hog below you that you may think you have E on can become a Hog zooming into gun range before you can blink.
Corsairs in general are among the best in high-speed maneuverability. They're one of the few whose rate of roll and aileron authority IMPROVES with speed (P-51 being a notable challenger). Very few fighters will hang with the F4U in a high-speed fight, particularly involving roll. Learn how to handle Der Uberflappen (TM)! The Corsair's flaps are among the BEST in the game, and you can get the first two notches out at speeds as much as 50-100mph FASTER than most other fighters (first notch comes down at 250mph TAS). The F4U is among the most maneuverable ships in the game between 250-300mph, and above that range is perhaps the top tier, threatened only by the Mustang and 109K-4 in high-speed handling (the Dora only rivals F4U-4 in speed).
Corsairs are tough. IMO they're a bit weaker in some areas than they should be (the engine is made glass) but they're well protected and can take a good deal of fire to bring down. She can absorb a .50cal snapshot and keep flying, and it takes a LOT of .303 fire to put a dent in her (it sounds like a gentle spring rain plinking off the armor

). Cannon are the biggest threat, but the same can be said of almost any other aircraft.
That being said, it takes practice to get the most out of ANY F4U. She's not a jump in and land 20 kills the first time up ride. The F4U-4 also carries a hefty perk price (and for DAMN good reason. Guaranteed if the perks were removed every F4U you ran into would be a -4 or Charlie) so if you die it gets expensive.