Hi scuberd:
There are many quality dry suits out on the market these days and most are made relatively the same way from relatively the same materials. There are suits made of neoprene that have provide thermal protection with little to no undergarments. These suits help to keep you warm by the thickness of the material. However like a neoprene wet suit, these suits compress with depth and loose some of their insulating properties. They also have high buoyancy characteristics requiring the diver to use more weight to get down. There are crushed or compressed neoprene suits that are less buoyant and less effected by depth, but require the diver to have adequate thermal undergarments to keep warm. There are trilaminate suit that have no thermal protection qualities at all. They rely strictly on the undergarments to provide thermal protection. Neoprene suits tend to be very resistant to abrasion but are heavy when wet and take long to dry. Trilaminate suits are lighter and fast drying but some may not be as abrasion resistant as their neoprene counterparts. There are also vulcanized rubber suits, but may who wear them are professional divers, diving in contaminated waters. Not that you must be a pro or be diving in contaminated water to use a vulcanized suit, as there are people who are not and use them regularly. Wrist and neck seals are made from two types of material, neoprene & latex. Neoprene will be warmer especially in the neck area. However some will argue that neoprene seals are not as reliable as latex at keeping you dry. I know those who use both and they tend to be happy with what they got. In the end shop around, ask questions. Seek the advice of others on this board ( hey its free ) and then make a educated decision on what type of suit you want to buy. I myself use a DUI CLX-450 trilaminate, with Weezle Extreem undergarments & Diving Concepts drive gloves.
Best of luck
.Arduous