Paros is my favourite stop in the Cyclades and consistently underrated. Less crowded than Mykonos or Santorini, much more authentic, and the beaches (Kolymbithres especially) are genuinely world-class.
Key tip: rent a vehicle the moment you arrive. I used Paros Summer Travellers (paros-summer.com) — they meet you at the port. One day with a car or scooter covers the whole island. Don't miss the Antiparos day trip — your car fits on the ferry from Pounta.