I used the AFE books, I also have the Trevor Thom Air Law/Met book and in general I far preferred the AFE ones. Much easier to read, and they have useful self-test questions at the end of each section. I used these in conjunction with the Confuser (essential) and did very well.
There's a confuser-type book as part of the AFE set but it's nowhere near as good as the 'proper' confuser.