I went through about 8 or 9 decks (bought in rapid succession, then passed on to other people) when I first started reading Tarot back in the early 90s, just because the shops I bought them at didn't have opened ones to look through and you couldn't look up the images online.
1. Aquarian (depressing)
2. Some Kabbalistic thing with Tree of Life diagrams and colour attributions and not much else (Turns out I didn't know *that* much about Kabbalah)
3. RWS (I thought it was butt-ugly. Still do, actually.)
4. Sacred Rose (bleah)
5. Motherpeace (Drove me crazy because I kept spending ages trying to line the cards up straight.)
6. Tarot of the Witches (*double* bleah)
7. Llewellyn Witches Tarot (1992 version) (Dropped out of Wiccan scene shortly after buying it.)
8. Karma Cards (too simplistic)
9. Rune Cards (crappy book)
Current decks I wish I hadn't bought:
1. Elisabetta Trevisan's Crystal Tarot (Gorgeous cards, but I really wish I'd paid more attention to the fact that the elemental associations for swords and cups are switched, because every time I read with this deck it bugs the hell out of me.)
2. Mantegna Tarot (Love it for the historical value, hate it for the Muses, who deserve better depictions than they get here.)
3. The Necronomicon Tarot (Which was actually a gift, so I have a bit of a sentimental attachment to the wretched thing. Lovecraft and Tarot are two great things that are really kind of crap together.)