Choosing just one means looking at the balance of raw performance, firepower, range, ruggedness, and flexibility. IMO, the P-47 does well in all, except in range (compared to the P-51). The P-47 was used quite a bit for CAS and light attack.
The F4U Corsair looks to be a good balance of factors, though the P-51's range was considerably greater and its performance similar. Fighter technology evolved pretty quickly before and during WW2. Models that were front-line in 1941 were obsolescent mid-war (e.g. the F4F and P-40). The Corsair and Mustang came a bit later and their performance was greater. For sheer accomplishment the F6F Hellcat was tops, but the F4U's performance was greater. Though obsolescent, the F4F (FM4, IIRC) continued use in escort carriers, due to the F4F's smaller size and mostly adequate performance.
Enough blather ... were I choosing for long range escort, the P-51 was better. For flexibility, the F4U. The P-38 and P-47, respectively, would be my runners up for those two roles.
One of the reasons for the P-47 (which did serve in escort roles) was its ability to absorb punishment as well, which made it a winner for CAS. Properly outfitted with an external drop tank, they also flew escort missions. The P-51 was described as a sweet aircraft, and easy to fly, the F-4U not so. The P-47 fell somewhere in between, The airfoil geometry of the P-51 was different, and that, coupled with the Merlin engine gave it a speed advantage over other aircraft. The P-51 probably had the best overall rating, and definitely the most kills of any allied plane credited, but there were other planes which performed workhorse duty as well. As an all around aircraft (which incorporates a series of trade-offs) I still like the Jug. The p-38 did well in the Pacific after Lindbergh and others sorted out problems with the aircraft and worked out tactics against the Japanese, and had the bonus of having a second engine, always nice over water. Another few worth mention are the Supermarine Spitfire (possibly the most eye pleasing aircraft design, ever), Hawker Hurricane, and the DeHaviland Mosquito, the latter being constructed of wood with virtually no radar signature.
(Note that we have confined our choices to Allied planes, leaving the Me Bf-09, FW 190, and Me 262 out of the discussion. Though the latter was only used in the later part of the war (too late to have sustained service and effect), it had the potential to be a game-changer, had Hitler not ordered it to be configured as a bomber in 1941)