I have never been diving in Outer Banks and have not heard much good about it. Most of the NC diving is out of Beaufort. The dives require long boat rides and short dives, as they are deep dives to wrecks mostly, but as they are in the Gulf Stream, I will say that it is some of the best diving I have done for seeing wildlife and general interest. Choosing a group to dive with depends on cost. The cheaper boats take a while to get out there and have TONS of people on them.
Discovery Diving Co.- NC's Diving Headquarters - Discovery Diving Co. The smaller boats zip out faster and may only carry about 6 people, but will cost more. We always opted for the latter. I can't remember the people used, but possibly Olympus? Here is a Board with good info:
NC Wreck Divers
I have tried to dive off Wilmington with some success. Like the guys at Dive Safari in Wilmington, but everytime I would book, they would cancel cause the "waves were too high". They did not have big enough boats, I guess. And the one time I went with them, it was not a great experience. Years ago, we got the boat we used in Beafort (the 6 pack) to meet us in Wilmington to dive there. There is a great old wooden wreck off Wilmington that looked very "old worldly" and you could still dig for bottles and other relics. Very cool.
Good luck!