The best Confederate general was Forrest, beyond any shadow of a doubt. The man was a born cavalry tactician.
The most overrated was Lee, who never used his forces appropriately from a strategic standpoint, considering his logistical limitations. After uselessly throwing away Pickett, Lee threw away men on a war of attrition that he was bound to lose, and couldn't identify a clear goal.
Grant was imbued with the same qualities that Bradley showed later, while Patton had a dash of Longstreet and a little more Forrest.
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.