If you haven't done any defensive training, take one of Jim Conway's own classes first. They're cheaper than the traveling guys he brings in, and they're a distillation of what he's learned from all of them. Once you do one or two of those, you'll have a better idea which of the traveling instructors interests you.
Another way to sample a bunch of instructors is to come to the Summit meeting that Jim's putting together on Superbowl weekend. A bunch of nationally known instructors all in one place teaching smaller blocks of instruction.