Depends on what you want
If you plan to lie around on the beach or by the pool the whole trip then I'd recommend the Maldives. Beaches will be fantastic and water will be awesome!
If, however, you'd like a bit of culture as well as a chance to lie around by the pool I'd go to Bali and spend 4 days in Ubud in the mountains amongst the rice paddies and 3 days at a resort hotel in Nusa Dua or Kuta. Bali's beaches are nothing special but it's culture and relaxed vibe are second to none.
Just depends on what you are looking for.