If you like Carnival I think you will like NCL. In my opinion each has certain things that they do better than the other. Give them a try. We usually go Carnival but intend to mix in a few NCL.
7 Norwegian: Sky, Jewel, Dawn, Epic, Pearl, Breakaway, Getaway
9 Windjammer: S/V Legacy X3, S/V Polynesia, S/V Caledonia, S/V Diamant, S/V Sagitta X2 S/V Mandalay