decks and how we think with them
I am also interested in the "WCS or Thoth" question and currently am really enjoying "WCS AND Thoth" as an answer.
One of the things I think we're talking about when we talk about different decks is also the thought and the books and other kinds of information available about them. When I think of WCS I think of Rachel Pollack's "78 degrees of wisdom" and its view of the cards as resonant fragments of stories (among other things). The Thoth deck seems to be more about abstract ideas and powerful but nonlinear unconscious archetypes. These are also contrasting styles of thinking.
Two books that are REALLY helping me to enter into the richness of the Thoth are "The Crowley Tarot" by Akron and Hajo Banzhaf, and "Understanding Aleister Crowley's Thoth Tarot" by Lon Milo DuQuette. The latter gives glimpses into alchemy, astrology, numerology, the Qabala, and the "big story" woven into the cards; the former gives a tremendous wealth of information about every single symbol and image in the deck. To give you an idea of how much information is in these books, Lon gives a 20 page chapter elucidating the design on the BACK of the cards. And Akron and Banzhaf give 4-5 pages on each of the trumps, but they're 2 columns of small print, so that's really like getting 16-20 pages on EACH CARD.
I found the imagery of the Thoth compelling but completely impenetrable until I started reading these books. Now it's incredibly rich (maybe a little too rich at times!). The book "tarot, mirror of the soul" tries to give some access to the cards in 2 pages apiece, but for me this didn't really help at all. Your mileage may vary.
I guess the reason why people recommend starting with WCS is that you can read a paragraph, or a page, and have a reasonable understanding of a given card... whereas with Thoth the "cost of entry" is a lot higher, unless you take a purely intuitive approach. The rewards might be greater too. In any case it's wonderful, wonderful, to have both these decks, and so many more, and so much thought and writing and discussion about them.
Start wherever you are, follow wherever the mystery leads you, take notes, and let us know what you find!
best to all,
Sybilant