I live in Stavanger too, and use a billabong solution 5/4/3. Have not used it yet in the depths of winter, but up until now its been good
Having a built in hood is not a necessity, but you will definitely need to get one if you go for a suit without one, after all, when it starts to get warmer again you will still need the suit but not the hood, i think its nice to have the choice.
I have heard good things about all of them, i guess its just down to preference. But anything in a 5/4 and up and you should be doing fine. Important thing is to make sure its a snug fit.
You probably already know this yourself, but if your looking around i know Triplehead in Stavanger have Xcel and Quiksilver suits, Session have the Ripcurl suits, and SurfSentrum have C-skins
Hope that helps you out