Reasoned:
I am going out on a limb here by making a very controversial statement but I believe that although the best/most unique looking planes belonged to the Luftwaffe, in terms of subjects being represented by the modeling companies, I think the Japanese are the most complete (perhaps due to Tamiya/Hasegawa/Otaki/Nichimo).
I'd agree that the Japanese aircraft are very well represented - at least in terms of kits. Depending on the subject, aftermarket markings are either glorious or a world of hurt.
The thing I don't know, just because I don't know Japanese aircraft as well, is if there are "variant holes" floating around. For example - Hasegawa makes a mean P-40E, K, M and N. In 1/48 and 1/32. But if you want to do a Merlin-engined P-40F or P-40L (which were rather common in Africa and Italy), you're stuck with an old, troublesome kit that doesn't hold a candle. And if you want to do a B/C, you kind of face the same (albeit with a few options).
Is there something like that with the Japanese aircraft? A fairly major variant of, say, the Ki-44 that's just not offered really? I don't know...