Duane:
They are all in your list: from south to north, Portmarnock, The Island, County Louth, Royal County Down, Royal Portrush, and Portstewart.
I strongly endorse playing the second 18 hole course at Portrush, the Valley course, as well. I might rate it equal with one or two of the others mentioned, but somebody or other would get mad if I did ... and I didn't say it was superior, just equal.