Lots of people complain about Progresso. We LOVED Progresso. It was beautiful turquoise water, friendly people, much better souvenirs than Cozumel, and the beaches were beautiful, too. We did the Carnival Uxmal excursion and loved~loved it!!
Cozumel is a nice, friendly port but the newer docking area is not beautiful like the old area so you don't get to see that beautiful blue-green water. The beaches here are fantastic. It's a flat $10 or $15 to the beach... up to 4 people... they have a taxi station and the prices are now set, no haggling. The taxis are clean and nice. There are some great shops by the port that sell adorable Christmas ornaments. We did our own beach day without Carnival...Nachi Cocom....loved-loved it.. perfect beach, loads of drinks, great water... would highly recommend them.