My top 10 favourite landscapes:

  
1. The Tepuis (table mountains) in the Gran Sabana, Venezuela
 
2. The north-western coast and highlands of Scotland, Great Britain
 
3. Iceland (esp. the inland desert, the volcanoes, glaciers and the south coast)
 
4. the Namib desert and coast, Namibia
 
5. The Alto Plano/the Andes in Bolivia and Chile
 
6. The north coast of Cornwall, England, Great Britain
 
7. The Arctic, such as in Svalbard or East Greenland
 
8. The Caucasus, Georgia
 
9. Cappadocia, Turkey
 
10. the sheer vartiety and drama of Big Island, Hawaii 
 
  
Also cool:
 
- The Grand Canyon, USA
  
- the Matterhorn and surrounding glaciers, near Zermatt, Switzerland 
  
- The fjords and mountains of Norway
 
- Palmarin in the Sine-Saloum delta, Senegal
  
  
- Brittany, France
 
- The Yorkshire Dales, Great Britain
  
- The Atacama desert, Chile
 
- The moonscape of the volcanic caldera on Fogo, Cape Verde
 
- Halong Bay, Vietnam
 
- Mt Ararat and the surrounding Anatolian plateau, Turkey/Armenia
 
- Blyde River Canyon, South Africa
 
 
- The Virungas, Rwanda
  
  - Kaieteur Falls breaking the endless jungle in the virtually uninhabited interior of Guyana
   
- The Orinoco delta, Venezuela
 
 
… and many more …
 
  
(Of course some of the world's most spectacular landscapes are not listed here, simply because I've not yet been to them. Once I have, they're more than likely to enter the list at the expense of some currently listed. E.g. the Sahara desert or Kamchatka or Antarctica are all likely contenders …)