It seems like Thom Yorke is the core songwriter and Johnny is the core arranger that gives the song its complexity.
I basically download every single one of Thom & Jonny duo bootlegs from THe Bends era to today. They are pretty much all spectacular
Although I am almost tempted to say Thom Yorke is Radiohead and remove Jonny Greenwood from that.
If someone asked me who is the greatest pure singer-songwriter (so one person singing with guitar/piano with no other person helping). I am tempted to say Radiohead even if there is no studio album demonstrating that as I don't think there is a better stripped down acoustic performer than Thom Yorke.
My conception of what Radiohead is about and what makes them great is they are essentially one man with an acoustic guitar singer-songwriter emotive music but then re-arranged initially as a alternative rock group and then art rock group.