1/2" drive means the little square where you put on the socket is 1/2" wide. Usually the 1/2" drives have a wider range of torque, but you need an adapter to use any 3/8" sockets or you need to get 1/2" sockets. I think the key thing is to look at the torque ranges you're going to be tightening stuff in, and get a wrench accordingly.

As for the dial type wrenches, they are a bit more annoying to use and little less accurate, but for most things they do the job well.