I at first thought the Cary-Yale Visconti had the worst cardback in the world - it was a plain beige.
Then along came the Blue Moon - nothing on it at all, just the white of unprinted cardstock. In fact, I have a subcollection of decks with the worst cardbacks in the world, and those two feature.
I think Crystal Visions has one of the most beautiful card backs. It is so 'girly" and beautiful. I have bought several of those decks for people based solely on the beautiful backs. Well, I mean I liked the cards themselves, but the backs 'sealed the deal". Everyone who has received that deck absolutely loves it and thinks it is so gorgeous.
It is late, but I will come back later to update the worst back.
Well.. I just noticed that I had already posted about the Crystal Visions' backs. I still think those are one of the best beautiful tarot deck backs around!
I don't have a favorite card back design but I know I don't like the really bright, busy
backs. They the cards are all laying in a spread with really loud backs, it's distracting.
I like something more non-descript, like the MPR backs. Something sort of plain.
I really dislike when there's a pentagram on the back. It leans towards all that
witchcraft stuff that people are afraid of. I never use a deck with that on the back.