Help with choosing a hotel

Hi. I need help with choosing the right hotel in Cancun or Playa del Carmen in early Jan. We are a couple in early 40’s, and looking for a 5 star , vibrant hotel catering for younger crowd, preferably adults only. A nice beach, preferably tolerating topless sunbathing , is a must . Distance to the city is not important.

There is lots of choice in both areas , so we are a bit lost and would really appreciate advice from experienced people. Thanks