Diani, Malindi or Lamu?

Trying to decide which area of the Kenya coast to visit for my first time in Kenya. I am thinking Diani, Watamu/Malindi, or Lamu. And recommendations on which is best? Or maybe you have other suggestions I am not considering? I was hoping to do some good snorkelling. We also enjoy nice beaches, history/culture, and good food. We are not as big into partying/nightlife. Thanks for your recommendations!