US by far!!!!
First of all, the Thatch Weave was a simple, yet brilliant solution to counter the more nimble Zero. Navy and Marine pilots use the the Thatch Weave up until the end of the war. The Finger 4 and echelon were superior formations than what the Japanese used, a flight of 3 similar to early British fighter formations.
Also, Japanese combattants were too given to Bushido which ended up having them quick to go down in a blazing glory rather than try to live to fight another day.
Also, the Japanese were plagued at all levels by complex planning and rigid execution. In contrast, Americans were much more willing to improvise as necessary.
To illustrate this last point, there was a famous Guadalcanal mission commanded by Joe Foss. There is now a famous painting depicting this mission. A very large Japanese formation was heading toward Guadalcanal. Foss took up his flight of F4's and some army P38's. Their flight of 12 planes were hopelessly outnumbered. Foss had them duck in and out of clouds all over the sky in an attempt to make it look like their numbers were more than what it actually was. The Japanese never attacked, but after some time, just turned around and flew back to Rabaul.
What was learned after the war was the Japanese had a decoy formation. Only when the Americans attacked the decoy, would other formations attack the Americans, and the bombers would work over Henderson unmolested. Well, since Foss never went after the decoy, the Japanese, paralized with rigidity, never executed the next step of their attack, and after their fuel ran low, just turned around and flew back to Rabaul.
Here's that painting:
http://www.daveswarbirds.com/cactus/paint_9.htm
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