The City Pier is closest to town; you can actually walk to Carlos & Charlies from there. The International Pier has the advantage of having the duty free shopping mall at the end of the pier; and, of course you are much closer to Chankanaab Park. In any event, a taxi ride to downtown is only $5 for the entire cab, not per person.
We just returned from Maasdam back-to-backs and in Cozumel, we docked at the International Terminal.
We had a FABULOUS time and love that ship. She has the most amazing crew and we loved every second we spent on board. She's the perfect size for us, great food....we had some truly outstanding meals and think Chef Mike Mahn is wonderful.
Any special Maasdam questions, ask away....I'll try to help.