If you want a fancy AGM, it's Odyssey or Northstar (sold as X2 Power at Batteries Plus). Otherwise, try to find any AGM made by East Penn (they're usually better than Exide or Johnson Controls produced batteries). Last I knew, the Duracell brand AGMs are East Penn, as are the West Marine house brand (SeaVolt) AGMs. Deka is made by East Penn too.
Personally, I have an X2 Power group 34 in the Jeep (replaced an East Penn made Duracell) and we run the SeaVolt AGMs in the boat.