It's remarkable to think of the accelerated development of Radiohead from Pablo Honey to The Bends to OK Computer to Kid A in 7 years. Each album was a massive leap from its predecessor and set up a legacy with which they have struggled ever since. They fared best with "In Rainbows" which slots in for me just behind "Kid A".
OKC felt spectacular - they were simultaneously in-step and out-of-step; guitars were in but they were twisting them beyond recognition at some points and letting them sing at others ("Let Down" being the most glorious example of the latter). They used robotic voices and strings. They used synth bass but just the once. They straddled the tedious "real music" orthodoxy of 1997 and the more experimental heads who were unimpressed with the way Britpop had solidified into Dadrock and were finding little in the mainstream. They were, in essence, the acceptable face of Prog Rock and had several buckets of tunes as well as a desire to shake themselves up on each album. It's a cracking album, flows wonderfully from end to end but it was that one last quantum leap that secured their status. That's for another time, tho'.