i live in jersey and dive year round ...
i own (or have owned) just about every brand and type of material made
for the coldest temps, i havent found anything to beat a bare super hi-loft
although the 4th element are nice, i have found one piece outfits to be more insulating
i also keep more body fat than the average diver which adds to my own insulation
i agree with the idea of layering but 39 degree temps and 40s are not the same ballpark so that determines a different set of layering for me.
sorry for sounding so opinionated, but i own all these because everyone is different and i can't simply take what people say as fact. judging from the fact that you have 4 pages of discussion on this in such a short time proves that ... there are so many things to take into consideration, for example, where are the people giving advice diving? how much do you want to spend? can you try them before you purchase so you know how they react to your body type/shape? (some of the materials stretch MUCH different than others) are you using dry gloves/argon/latex hood/heated vest etc which can all change your level of comfort in the temps you'll hit
in the end remember, everyone is different and if you can use before buying, you'll find out more than reading will teach you (in this circumstance)
hopefully no ones feathers are ruffled enough to attack ... ;-)
dive safe