NCL and Carnival are 2 different products with 2 different experiences. Although the Epic has some dynamite offerings and the ship is gorgeous, Carnival has some fantastic amenities. Carnival's Freedom is a very large ship and it does have the water works, they have a great children's program, really good food, and some good shows. I don't think you'll be disappointed with either cruise line. For a first experience, I would suggest going with the ports that interest you the most and the price. If NCL is less expensive, try the Western Caribbean itinerary if the Eastern is not to your liking. If the price is about the same, go with the itinerary you prefer. There will be plenty to do on the Freedom if you choose that ship, and there is plenty to do on the Epic if you choose that ship.
We're all waiting to see what you decide to book