As several posts here have said, the brilliance of a leader all depends on what and where we are talking. Zhukov was e.g. in my eyes not a great general. His tactic was the so-called "human-wave" tactic where his forces would mount massive attacks by all the available means and thereby taking advantage of overwhelming numbers of men the russian armies possesed.
Guderian, which was one of my favourite leaders before, was dropped on my list after I read into a little bit more of him. As someone stated before it's true that it's som kind of myth that he invented the "Blitzkreig" doctrine. It was, correctly stated above, Charles DeGaulle that laid forward the first basic tactics in using tanks a spearheads in a fast advance deep into enemy lines (this already as early as in WWI). What Guderian did was that he altered the basic ideas a little and had the luck to bring the ideas into the very conservative german general staff. He was also, by an accident, the one that convinced Hitler to use the tactic during thr France campaign.
Another one of my old favourite leaders was Rommel, who I also have dropped a little bit on my list after reading into a little bit more about him. Without going to deep into what he did, I can say that it was more luck than skill that created his brilliance.
But what leaders is great then?
If I shall take one during WWII I would pick Gotthard Heinrici. The german general that was assigned to defend Berlin against the russians in the end of the war. His forces composed of a mix of old men, young boys, reserves and homeguard soldiers. He faced a russian enemy that outnumbered him atleast with 10:1 and that also had unlimited supplies of both ammunition and fresh soldiers. Still with this odds he managed (sadly to say) to keep the war alive for one more month as the russains didn't manage to break his defense. What constituted his success was true brilliant defensive tactics. It should also be noted that he didn't just succed in his tactics in front of Berlin. During the retreat in russia he managed to several times halt the russian offensive so that other german units got the chance to retreat backwards, this often meeting a enemy force with an overwhelming odds considering men, weapon and logistics. If u want to go deeper into this defense orientated generals achievments u can look in the book "The last battle" written by Cornelius Ryan (same person who wrote "A bridge to far").
I also have to put a note on my absolute favourite character of the second world war; Michael Wittman. As I'm a tank soldier myself in the army I cannot say anything else than that I'm impressed by this man. Michael Wittman was the german farmer that became the most succesfull tank commander in the whole WWII. He's tank took out over 200 (!) enemy tanks during the war and a lots of more artillery pieces. June 13th 1944 he and 3 other tanks took out 25 british tanks by there own, this even after his own tank got hit and he rushed away to grab another one!
Wanna read more about this the ace of the aces on tanks during the WWII:
Wittman 1 Wittman 2
