Which GPS?

Ok ,I am breaking down and buying a GPS....for the most part I only drive and show property in St.Augustine/St.John'sCounty where I am very familiar. I recently have been showing homes in Jacksonville and even Palm Coast. While mapquest is wonderful, I really would like to have the convenience of a GPS mounted right on the dash . My Blackberry has the GPS feature but is too small to see. I know prices have come down and there are so many to choose from. Any advise in the best one?