Lee was probably the better tactical general, but Grant was definitely the better strategic general. As I've said before, Lee's reputation is greater than it ought to be because of him facing McClellan early on.
Grant had the key strategic insight that none of the Union Army of the Potomac commanders before him had had: once the Army of Northern Virginia was eradicated, the war was won, and the North could replace lost men, weapons, and supplies but the South couldn't. 1864 in Virginia was a brutal, slow campaign but Grant could replace his losses and Lee couldn't. McClellan and Hooker and Burnside didn't have the stomach to do what was needed to destroy the CSA. Grant did.
