That's such a rare all-time favorite, I feel, but excellent taste all the same. I'd go with "Reckoner." Easily. And I know all Radiohead fans love answering this stuff, so a follow up: your favorite album?
Amnesiac! I think it was because it was the first record of theirs I bought on the day of its release, in nerd-like anticipation. Reckoner is such a great song. I will never forget the night the band released the In Rainbows audio files and I listened to Reckoner for the first time. I was expecting a cleaned up version of ‘feelingpulledapartbyhorses’ but was awe-struck with what played instead. I thought “fuck, they’re still are the best band on the planet”
What’s your favorite record?