The Kool Korner grocery has wonderful Cubans for lunch. It's near midtown Atlanta just off the Georgia Tech campus. The place is a dump but it's run by a Cuban guy who loves his work.
It's at 14th St. and Atlanta Ave. about a half mile west of I-75. Cash only, lunch only, to-go only but for $3.50 for a full-size Cubano with the works, it's worth it.