Oasis (musical group)

Rory Williams preferred Oasis over Iron Maiden. He noted this when Merlin threatened to use an actual iron maiden on him, whilst he interrogated him about the Pandorica. (AUDIO: The Once and Future Nurse)

Behind the scenes
Though Rory doesn't explain this, Iron Maiden and Oasis are both 20th century music bands. Specifically, Oasis were a rock band.