The first 7 responses answer your question pretty well.
If you are going for the decor, buffet, covered pool, newer ship, take the Majestic.
If you are going for Alaska, take the Crown, anything but a Royal Class ship.
Also, if you are going for the ship, don't go to Alaska, go anywhere else. Alaska cruises tend to be more expensive than other destinations.
My opinion, take the Crown to Alaska.