There are a dozen threads with a dozen opinions on this one...
The first recommendation many here might make will be to take a drysuit class (
http://www.scubaboard.com/forums/basic-scuba-discussions/450470-buy-drysuit-take-class-first.html). You'll get the opportunity to try on a few, as well as learn the differences between the types. Secondly, you'll gain a better respect for features you like, and identify the ones you don't. Play close attention to tri-lam vs neoprene, inflator and exhaust valves, latex vs neoprene seals, and integrated boots vs rock boots, and fit.
Your budget will be a contributing factor to your decision making. Used suits may play a large role in mitigating the expense a little bit.
Size may be another issue for you which is why it will be important to try many suits on, just as when purchasing a wetsuit. Only this time, you'll want to have room inside for undergarments. Speaking of which, I suggest reading a few threads on undergarments (
http://www.scubaboard.com/forums/exposure-suits/445656-warmest-undergarment-available.html), bouyancy with the suit vs bc, and weighting options and techniques.
I just recently purchased a Mares TechFit LX and a Fourth Element Halo 3D undergarment, and I like them both. Bare, DUI, Santi, ScubaPro, and many others all make good quality suites from what I've read here on the board.
Best of luck to you. I'm sure this thread will explode with advice and opinions in no time. Pay attention to others experiences, but make sure you gain some of your own before dropping 1,000 euro on a full drysuit setup.