...as far as I know. I'd love to hear which decks you find good to use - beautiful decks, decks with strong characters, decks that have shown you something new.
While I don't physically use it any more, the Rider-Waite-Smith was the deck I learned from, and I've found that it provided a strong foundation for my understanding of tarot in general; in some of my card articles, you'll see that I've framed cards in other decks in terms of how they differ from the RWS, as if the RWS is the default. I'm sure many readers do fine without this; after all, there are other important decks that have echoes everywhere, the Visconti-Sforza, the Marseilles, or the Thoth. But knowing the RWS has helped me out a fair few times.
There are a million zillion RWSs to choose from; I used the Universal Waite, which is less bright than most available options, but I find that makes it easier to explore the images, to see them as three-dimensional. YMMV.
RWS aficionados might like to read the RWS Copyright Faq: barring rapid new legislation, the RWS copyright will expire no later than 2012. At this point it will be legal to take the original RWS and print it, mod it, do anything you like with it; no one will own the images any more. But as JB Hare's comparisons point out, good luck getting images of the original deck; it's been subject to numerous tiny modifications in the past century. (The Pictoral Key To The Tarot is more cut and dried; in 2012, those words will be yours, mine and everyone's, end of story).
The most beautiful decks in the world are the Osho Zen, the Intuitive Tarot and the Roots Of Asia. I've worked with all of them; the the Osho Zen has a heck of a personality, and - just watch it - will give you far more Major Arcana draws than is remotely statistically possible. It has a Zen sense of humour. It gives its own names to all the cards, often showcasing an aspect of the card that other decks ignore. Its accompanying book contains many extracts from Osho's writing, and they will make you feel happy when you read them. Most of the card articles I'm writing here include Osho Zen images. While it doesn't seem like it'd be a good starter deck, the one I used to play with was the first deck of a great reader (and great friend).
The Roots of Asia is very calm and full of new insights. It's a deck so good you'll hardly ever need it. I confess I barely used the Buddhist booklet that came with it, but Buddhist tarot users may be interested in integrating dharma with Tarot. It's full of life, and uses nature/animal imagery heavily. Human figures are a gorgeous mixture of Indian art and Cubism.
And I've only just started working with the Intuitive deck; this blog is partly an attempt to get to know it (her?) better. It's quite pastel, and surrounds each card-image with a coloured oval, on a card almost as wide as it is tall. I was also drawn in by the notebook approach - that it was a deck that you can write yourself - though I seem to have started a new blog instead. ;_;
There's a few other strong decks I've used;
The Dragon Tarot was one of the first two I used; my sister and I purchased that and the RWS together one January afternoon in 1999. It wasn't so useful for learning as the RWS is, but it's got strong elemental energies.
The Mythics came with their incredibly useful hardback book. The cards, and the book, assign a Greek god to each Major card, and a story to each suit from Ace to Ten. Each court card is represented by a hero. It's a wonderful way to learn more about the Minor Arcana, one I still hold in mind when I read; I had to give the deck itself up, however, because its fierce personality grated a bit with my own; it's the only deck I've ever argued with.
The Medieval Scapinis have quite a pull, and they're smart as hell, but they're difficult to use, partly because of the pip cards - ornate, but not representing anything.
Yoshitaka Amano's Tarot has very plain pip cards, but the illustrated Majors and Court cards are of interest if you want a look at the Tarot that is rooted in Japanese myth rather than in Western thought. If you want them, you'll probably have to order them from Japan.
I've never used the Robin Wood, but I've flipped through it, and if you've known the RWS then the Robin Wood is a really fascinating rewriting of that. It seems to use a lot of Wicca imagery.
A word on the Thoth deck; it's quite beautiful, in a way that relies heavily on its symmetries, but it gives me the creeps. I don't think anyone comes to the Thoth with an open mind, and certainly before I first saw it I'd heard enough stories about its energy being unsettling... As with everything, I'm sure someone likes it, but I don't. Every image looks like an idea I grew out of years ago, and it feels unpleasant to look upon. However, I believe it's Alan Moore's preferred deck, so there must be something to it.
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