I have an old Jane's Navy Fights book here somewhere that I nicked from the library in highschool, lol.
On the question of which aircraft is better, well, depends on how you want to use it and HOW you used it.
In terms of over-all flight performance, the F4U was faster, had a tighter turn radius (droppings its flaps it could turn with the Seafire and was able to maneuver with the Zero at high speeds), faster acceleration and a better roll rate. It's disadvantages included floating at ground effect when it was about to land, due to the large wing area, and it's infamous flaws when it came to carrier operations: stiff, bouncing oleos on the undercarriage, poor downward visiblity and the unpredictable drop of one wing at low speeds. The US Navy didn't clear it for carrier use until 1945, but the Marines used it from 1943 onwards, and they certainly didn't complain. The Corsair, however, was a 'world beater' with performance that could match any FW-190, P-51, A6M or Spitfire.
The Hellcat, on the other hand, was clearly, the inferior aircraft in terms of flight performance. BUT, it was ridiculously easy to mass-produce, it had greater range, it was easy to land and easy on the pilot. Because of this, it was used more extensively than the Corsair. Of the 6,477 aircraft that the US Navy destroyed in WW2, the Hellcat accounted for a staggering 5,256. Ace Lt. E. Valencia (23 kills) made the famous comment that "These Grummans are beautiful planes. If they could cook, I'd marry one."
To compare, here are some rough stats:
http://www.microworks.net/pacific/aviation/f6f_hellcat.htm
and
http://www.microworks.net/pacific/aviation/f4u_corsair.htm