I have only owned about 15 decks in my lifetime and I got rid of about half of them. Guess I'm a little picky when it comes to my decks.
~Aquarian Tarot - this deck was just ugly.
~Tarot Illuminati - again, too ugly and too CGI. I couldn't bring myself to look at the deck more than once.
~The Night Sun Tarot - same issue as above.
~Druidcraft Tarot - I didn't outright hate this one, but it didn't read well for me so I passed it on to my sister.
~Anna K - I still have this one, but I really dislike the ugly "mustached" men and women. It wasn't worth the price.
~Wild Unknown - WHAT? Yep, I really regret purchasing the Wild Unknown. I got the 1st edition and I bought it at full price from Etsy. If I had purchased the current mass-market deck, it might have been worth the price. The art is beautiful, but the cards are so bare. I LOVE seeking out hidden symbols in tarot, and there's nothing there to find...
There was one deck that I regret giving away, and that's the large print Thoth deck. I really loved the artwork, but I was trying to downsize my collection at the time as a part of my minimalist lifestyle. I had this idea in my head that I shouldn't keep a tarot deck that I don't read with. Ugh... such a bad decision. There are so many times that I've wanted to study the Thoth deck since.