The best Confederate general was Forrest, beyond any shadow of a doubt. The man was a born cavalry tactician. Forrest was a great calvary commander (infantry on horseback), but he commanded far less men than Jackson, and his victories were relatively minor battles (Brice's Crossroads was probably his greatest). But, it's a matter of opinion - there are good people who pick both.
I feel the most overrated general was Grant. He won only because he was willing to sacrifice so many men to do it. He was not a brilliant tactician.
I believe that Grant was brilliant in his own way.
He was brilliant in determining the center of mass of his opponents and then using bulldog tenacity to attack it.
Others had long believed that Richmond was the center of mass of the South. Others believed it was their productivity....ergo, Sherman's march to the sea.
Grant determined that their center of mass was Robert E. Lee himself. He was so VERY, very right.