My list, in order of priority:
1. Kenya/Tanzania safari
2. Seychelles
3. Chile patagonia
4. Santorini, Greece
5. Big Island, HI
6. machu picchu, Peru
7. Galápagos/Easter Islands
8. Milford Sound, New Zealand
9. Rio de Janeiro/ Amazon
10. Marrakech, Morocco
As you can tell, it's all about adventure, history and science for me.
There are many more, but these are definitely the top ten.