I read an article in the August 2002 issue of Flight Journal on Corky Meyers (Grumman test pilot). He was the test pilot for the F7F Tigercat. This is from that article:
"For many years, Capt. Trapnell was the top test pilot in the Navy; his word was law, both in Navy and industry flight-test circles. An example of his influence: he came for a three-hour flight evaluation of the first XF6F-3 Hellcat soon after its first flight and he gave the official Navy go-ahead for mass production on that day! The Hellcat eventually passed all of its contractual demonstrations two and a half years later, after more than 8,000 aircraft had been delivered to fighting squadrons! Also, to his credit, the Hellcat racked up a record 19 to one kill-to-loss ratio-the highest recorded in WW II.
When he came to Grumman to conduct the preliminary evaluation of the Panther in early 1948, I was the only Grumman test pilot who had flown the company's first jet fighter. At every opportunity during his three-day evaluation, I tried to pry his opinions out of him; his only responses were grunts, which I interpreted as, "Cool it, Corky!" At the end of his evaluation, as we walked out to his F7F-4N Tigercat for his return trip to the Naval Air Test Center, I proudly told him that I was the Tigercat project pilot from 1943 to 1946. He immediately burst into a diatribe about the Tigercat's many deficiencies: the over-cooling of the engines; a lack of longitudinal stability; excessively high dihedral rolling effect with rudder input; the high, minimum single-engine control speed, etc. He ended his oration with: "If I had been the chief of the Test Center at that time, I would have had you fired!" Each criticism of the Tigercat was absolutely correct. I was devastated and fervently wished that I hadn't gotten out of bed that day.
Just as we reached his Tigercat, I blurted, "If you dislike the Tigercat so much, why do you always fly it?" He explained: "The excess power of its two engines is wonderful for aerobatics; the cockpit planning and the forward visibility in the carrier approach is the best in any fighter ever built; the tricycle landing gear allows much faster pilot checkouts; the roll with the power boost rudder is faster than the ailerons; and it has a greater range than any fighter in inventory." Again, he was absolutely right. As he climbed up the ladder to the cockpit, he turned around, grinned and told me, "It's the best damn fighter I've ever flown." I realized he had thrown the entire test-pilot schoolbook at me with his succinct tirade and that we were probably pretty close in our opinions regarding the handling characteristics that define a really good fighter. I went home happy that night."
From that I would have to give the Tigercat a vote in the race for "Best" fighter of WWII.