I liked Oblivion better, it was clearly the game the developers cared for more, and it was set in a world that fits my gameplay style much better (I really hate guns). Not saying that Fallout was a bad game at all, I mean I loved it, but after the main story was over the novelty wore off for me. When you're done with both games Oblivion tells you to go become a god while Fallout tells you to go die in a fire.
Two favorites for each game as far as location:
Oblivion- 1.All Aleid ruins, because they look awesome and I love the traps
2.The Dreamworld in the "Through a Nightmare, Darkly" quest, because I love when a game takes away everything you rely on and makes you use your head again.
Fallout- 1.The underground section of Rivet city that kills you mercilessly with its awesome traps, including the room of fire that I will never forget
2.Tranquility Lane, because it was another one of those beautiful mindfucks that I've come to adore
Two favorites for each game as far as location:
Oblivion- 1.All Aleid ruins, because they look awesome and I love the traps
2.The Dreamworld in the "Through a Nightmare, Darkly" quest, because I love when a game takes away everything you rely on and makes you use your head again.
Fallout- 1.The underground section of Rivet city that kills you mercilessly with its awesome traps, including the room of fire that I will never forget
2.Tranquility Lane, because it was another one of those beautiful mindfucks that I've come to adore