If you were a diver, then a big watch face is a plus, imo. The 39 - 40mm subs are too small in the murky depths and the 47mm + divers don't look out of place when strapped on a wet suit or just wearing at sea. Unless you have a big wrist they can look a little strange on dry land, however.
In fact, if you were a serious diver you would not wear a dive watch while actually diving. While I appreciate the history and aesthetic of dive watches, I never wear one diving. Wrist mounted computers / digital depth and bottom timers are what are worn nowadays.