It would be good if you described what you're looking for. Are you a couple? A family? Sun and sand types. Party animals? Young singles?
I think the Marien is a wonderful resort but for families, couples, and mature travelers. Nice rooms, good a la carte restaurants and buffet. It's pretty quiet though, unless you bring your own party with you. Close to Puerto Plata where you can dance in typical Dominican clubs, outside of the Playa Dorada complex but not far from it if you like tourist discos. The Malecon is really nice and you can walk from the Marien (5K). I can't compare Sosua. It feels really touristy to me but I only spent a day there. But it might be a happening place for young singles. You can always take a bus to Puerto Plata and return at night by taxi and visit Cabarete (famous for it's windsurfing) as well. That's an advantage for a first-time visitor.