Though I know that the question was favorite "song" and not "songs", I am completely unable to answer that without naming an extensive list. My favorites have seemed to fluctuate over the years, here are some that have been favorites at some point in time or other:
Street Spirit
The Bends
Just
Paranoid Android
Let Down (first Radiohead song I even liked)
Climbing Up the Walls
Electioneering
No Surprises
Lucky
How to Disappear Completely
Idioteque
Motion Picture Soundtrack
You and Whose Army?
I Might Be Wrong
Pyramid Song
2+2=5
Where I End and You Begin
Myxomatosis
Wolf at the Door
Punchup at a Wedding
Sit Down, Stand Up
I Will
There There
Killer Cars
True Love Waits
Sheesh, you sure wouldnt know that I havent even listened to a Radiohead album in the last year. Sadly, I also feel like I probably left some songs out that I should have included. Oh well, naming my favorite Radiohead songs is like naming my favorite U2 songs, next to impossible without making a gigantic list.
I'm not a huge RH fan but I do like Creep, Pyramid Song, You Might Be Wrong.. and there's another one that I don't know the title of. Lyrics go something like ' just because you see it doesn't mean it's there' Or something like that anyway.
I'm not big fan of them... but some of my favorite Radiohead songs are: How To Disappear Completely, Street Spirit (Fade Out), Life In A Glass House, Let Down, 2 + 2 = 5, Banana Co., Fog, Pyramid Song, Karma Police, etc.
You are all forgetting Fake Plastic Trees- unbelievable but along with that i'd say my favorites are- Bulletproof, motion picture soundtrack, paranoid android, karma police, the bends, no surprises.
where i end and you begin
scatterbrain
exit music
pyramid song
knives out
everything
idiotheque
paranoid android
street spirit
2 + 2 = 5
a punchup
morning bell
you and whose army