I have 'The Crowley Tarot' by Akron and Hajo Banzhaf. It is Purple and it is good for interpretation and background. Haven't looked at some of the others mentioned so I can't make any great claims for it compared to them but it is well worth looking at.
I received my Thoth deck from rubes on Wednesday. I also got the "purple one" (book) from her and the Ziegler book at Half-Price Books today. I'm glad to hear that they're both recommended books. I guess I'm ready to get a start on this deck.