That's interesting that you enjoyed AMSP. I think it combines some of their established elements into a gentler overall sound. I've heard quite a few non-fans say they enjoyed it. Similarly many kind of came back to or discovered them via In Rainbows, which was a much warmer album for them at the time - it's my personal favourite along with The Bends and would be my suggestion for a way in if you don't already know it.
Some felt they then returned to being somewhat cold and unapproachable with the next album, The King of Limbs. While I'm a huge fan of them, I do understand why many find them aloof and inaccessible.
I would agree that In Rainbows is probably the best way into the world of Radiohead. It combines a lot of their elements into one album without being difficult to access.