Re: Who was WWII's most important leader?
Goering did have underlings willing to stand up to him, and they generally paid for it. Adolf Galland stood up to him all the time, but was too valuable to expend for Goering's ego. Even at that, Galland was sent, near the end of the war, back onto flying status, with the expectation that he'd eventually be shot down.
If Galland had had his way, the Battle of Britain would have been fought with He-112s or He-100s instead of the slower, less maneuverable, shorter-ranged Me-109s. Of course, at this time, he was too junior to have much of a voice in policy decisions like this. Still, as a front-line commander, his opinion should have counted more than it did.
Then, with Goering's emphasis on bombing, the best fighter pilots were pulled to fly Stuka dive-bombers, which were handily shot down by Spitfires. The Me-109s were assigned to strict close escort duty for the heavy bombers, which negated the speed advantages of the Me-109.
Galland also butted heads with Goering over the use of jets as light bombers rather than fighters. At every step of the war, when Galland was given a free hand, the Allies had a rough go, and when Goering pulled rank, the Axis suffered. The Battle of Britain was won by the RAF with no margin to speak of. Even a tiny bit more advantage for the Axis would have changed the face of the war.