I still think My Morning Jacket is about as good as it gets live and have seen them 5 times. Hard to pick a favorite, but probably when they played in Charleston at the Family Circle Cup tennis complex. Other great concerts I have seen include:
Pearl Jam in Columbia, SC
Fleet Foxes at the Tabernacle in Atlanta, GA
Deer Tick at the Pour House in Charleston, SC
Modest Mouse at the Music Farm in Charleston, SC
Phish at the Coliseum in Charleston, SC
Deer Tick, Futurebirds, and Dead Confederate at Buckhead Theater in Atlanta, GA