Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
I went for 5/3 and mostly diving in tropical waters.
One other thing to consider, as every is different, is a good hooded vest. I use my 5mm often and could not believe the difference a hood makes in staying warm. Many people can "gut" their way through one dive, but if you are getting cold, it is hard to get back into the water. Most of my dives are multiple and I hate to be cold. I ALWAYS opt for more neoprene as to less.
What brand did you go with?