Stilwell is a good one, namely for his bravery and fearlessness of death and capture (by the Japanese!)
Kesselring was a great commander and strategist, but he was a war criminal and murderer, so he doesn’t count.
I would have to suggest George Kenney
http://en.wikipedia.org/wiki/George_Kenney
Joseph Goebbels, maybe he’s not underrated, but imo, he was a genius, a very evil genius, but there was no one on the allied side who could compete with Goebbels in the game of propaganda.
I think Hollywood, Walt Disney, Doctor Seuss ect, although not one mind like Goebbels, gave him a run for his money. We had grannies and little kids making bombs and planes right here in the USA.