Anthem is my favorite as well. Picked up a first edition a while ago, was hoping his book tour would have taken him near me so I could get it signed but looks like he stuck to the coasts and Texas.
Thirded for Anathem. It isn't for everyone, you've got to have a high tolerance for made up words and enjoy puzzling things out but if that is you (likely if you read HN) then it is great. Probably my favourite sci-fi book ever by number of re-reads!
I really enjoyed it as well. I’ve enjoyed everything I’ve ever read from Stephenson.