Well, now that I've heard each and every Radiohead album all the way through at least 4 times... I can say that my overall faves of theirs are Exit Music (for A Film), There There, Reckoner, Packt like Sardines, I Might Be Wrong, Idioteque, Sail to the Moon, Climbing up the walls, and Lotus Flower. Oh, and All I Need. Really, all of these are from OK Computer forward... I think that really says something about their early work.
My favorite albums (in order) are Amnesiac/In Rainbows/Hail to the Thief (tied), OK Computer, Kid A, King of Limbs, The Bends, Pablo Honey.