I love both types! If an Island, I would choose the Maldives or Seychelles for the unique Eastern and Indian feel. If a city, I would pick either Sydney for the Australian nightlife, or Mumbai to visit the Taj Mahal (which I have not yet seen) and the curry!
If you could go anywhere on your next vacation - forget about time and money for a second - where would you go? Tell me! I'm dying to know.