It's hard to tell how good the Buffalo could have been since the highest performing (overall) version, the F2A2, never saw combat. The Finns were verry sucessful with their B239 models, though this was due largely to the skill of the pilots. The F2A-3 used by the Marines was probably the worst model, very underpowered, realitively slow, and overweight. The B339E was about as bad, despite being converted from the F2A-2, it had less power and was much heavier, as well as a reduced armament. So no wonder these two models got a bad reputation, especially when facing zeros.
Though even the F2A-3 had slightly higher performance (slightly faster, more agile, and better climb) than the F4F, but the Wildcat was alot tougher, which was its only distinct advantage aganst Japanese fighters, though it was still generally outmached by Zeros. The USN couldn't realy meet the Japanese on even odds until they had the F6F and F4U available. But still with good pilots, I'd say the F2A-2 would be superior to an F4F-3 or F4F-4 in a dogfight. Faster (344 mph top speed), better climb (~2,500 ft/min), more maneuverable, better visibillity, equal armament to the F4F-3 and longer firing time than the F4F-4 (plus the F2A had 2x nose guns which were more acurate than wing-guns), and somewhat better range. Though the F2A2 was a bit more fregile than the Wildcat it was alot harder to get a bead on and still was tougher than Japanese planes, particular in respect to pilot protection.
Also, at Midway, remember that the USMC pilots flying the F2A-3s were inexperienced, and tried to engage in WWI style dogfights with the Japanese. I doubt they would have fared much better in Wildcats, or even F2A-2s for that matter. Though they might have done better in P-40s (or maby even P-36s) since they had good maneuverabillity, decent speed and power, good armament, simple and easy to fly, and were quite tough.
As a note on the P-39, in most respects it was superior to the P-40, and both performed rather poorly above 20,000 ft, the British even found their Airacobras more maneuverable at high-speed than the Spitfire iirc (the stick was heavier at low speeds, but was much lighter than the Spit at high speeds). However it was not thet easy to fly and had some nasty stall characteristics, (though the flat spin was only noted when the nose was improperly loaded) though buffeting usualy gave enough warning as long as the pilot was attentive. It was probaby no trickier than the P-38 overall.