I’m going on that exact Eastern itinerary on Holland over Christmas. I think it’s a much more interesting itinerary with a lot more things to do. Both would be good for a first cruise, but I’d choose the Eastern one, everything else being equal.
I really dislike Cozumel—it’s overcrowded with tens of thousands of passengers, multiple docks, and bad duty-free shops you have to walk through before facing a crowd of pushy vendors on the streets, which are dangerous. Also, downtown had recent shootings. I also didn’t like the Cayman Islands, as it’s a tender port with tons of ships. Jamaica doesn’t feel too safe either with pushy vendors. The Eastern itinerary has more smaller, beautiful islands with fewer ships in port. San Juan gives you a mix of modern areas, history, and places where you can use dollars.