Ascension Island, without a doubt.
Did my mapping campain for my Master thesis there (in Volcanology) and stayed for 2 months.
This place has a really special feeling to it.
It is really really beautiful, the feeling of having water around you for 1000 km in each direction, living on a 10x10 km big speck of earth. Beautiful skies in the night, catched a full moon eclipse by chance, all was light and all of a sudden dark and milky way emerged. A moment I will never forget in my whole life.
Wild donkeys following you around, trying to steal your food and even break into the kitchen over night. All these beautiful volcanic features. Turtles, sea birds.
On the other hand, all these wires, trying to catch all data from the air. A runway long enough to ground a space shuttle. Military buildings, all over the island.
Socially very interesting too - no permanent residents are allowed, so everybody just "spends their time" there. Nobody really is at home there and take any steps to make something beautiful out of their houses, for instance. No crops. You´ll have to wait for fresh food when the ship comes every three weeks. Drinking water comes from Devon, by aircraft.
One guy, from St. Helena ("Saints"), living there for 40 years but can´t wait to get to St. Helena, home, once he is retired.
Such an ambivalent place. Would love to go back there at some point in my life.