I think that the slaveowner Grant (Lee owned no slaves, although his wife did) was a decent general and in a way he helped the south through Reconstruction (he refused to go along with many of the more humiliating proposals). I think he was probably dogged by a huge inferiority complex because he was never anyone's choice to lead the Union troops, the top choices either fought for the Confederacy (Jackson, Johnson, Lee, Stuart) or failed (McClellan, Hooker).
Interesting points. I admire General Longstreet, too, and he was a close friend of Grant's. Complex people, both of them. One of the facts I remember about Grant is that, although he wasn't a very good student over all at West Point, he got top marks in horsemanship. My oldest daughter is in equestrian sports, and she's got an interest in the military academies.