Robert E. Lee and James Longstreet have always been some of my personal favorites, at least in the ACW era.
World history wise... I'll make a list.
Hannibal
Saladin
Davout
Wellsley
Montgomery
Bradley
Eisenhower
Rommel
And while I can understand criticism of Rommel, he was a fairly exeptional general in his field. Even when leading the Afrika Korps he did better than most other generals of the time would against old Monty and Patton.