For exposure suit, you'll probably need to get one thick wetsuit (7mm, farmer-john, semi-dry) for diving in your local water and another thinner wetsuit (3mm) for diving in warm water. If you find that you enjoy diving locally, you might end up purchasing a drysuit at some point.
For BCD, it will depend on what style you like best. I recommend trying out a conventional jacket BCD (you probably got certified in such a BCD), a rear-inflate BCD, and a BP/W rig. Do at least one dive in each BC to weigh the pros and cons of each. Joining a local dive club can help introduce you to other local divers who are often very generous with offering to let you try out their gear. By joining a club, you will also start to build your circle of dive buddies. That's a good thing. Some local dive shops will allow you to try out gear in their pool. Take advantage of this if you can.
For reg setup, I'd recommend getting an environmentally-sealed first stage since you'll be diving cold water. Many brands/models will fit this requirement. You should know that certain second stages have design features (heat exchangers) that make them perform better in cold water. What you choose should ultimately depend on whether it can be serviced by a trustworthy local reg repair shop. Regs can be finicky bits of dive gear, so it's very convenient to be able to drive down to a local shop to get something tuned or fixed competently/quickly. Something that most novice divers don't realize is that the breathing performance of a reg has more to do with the skill of the reg repair tech who last tuned the reg than any perceived differences among brands.
For a dive computer, there are many choices. You should know that a dive computer is not a necessary piece of dive gear; one can dive using tables -- but this requires that you use a depth gauge and timing device. You should consider the various features that are important to you. I prefer a wrist-mounted, nitrox-capable, easy-to-read, easy-to-use, PC-downloadable dive computer with a user-replaceable battery. A gauge mode and backlighting (or phospholuminescent display) are also very useful features. Other people think that air-integration is important or a hoseless/wireless transmitter (showing remaining tank pressure) are pretty neat. A computer can cost $150 - $1,000+.
I'll let other people discuss other pieces of dive gear. The buying-new vs. buying-used debate is often discussed here on SB. Something to consider is that many people get out of the sport for various reasons and end up selling perfectly functional dive gear at a significant discount from MSRP. If you are contemplating buying used dive gear, you should do enough research to understand the value of the item and how much it would cost to repair/service it (should that be necessary).
You'll notice that I didn't mention any brand names in my post. There are many reputable manufacturers who produce reliable dive gear. You are probably already familiar with most of them. When parsing through the various opinions that you'll get on this thread, ask respondents specifically why they chose one brand/model over another. Personally, I tend to give more weight to opinions offered by individuals who have tried/owned several different brands and those who don't have a clear conflict of interest (dive shop owner who sells Brand "X").
Good luck with your gear purchases...
