* Good effort put into the design of the card faces. I have a few decks with 100% standard faces, but those are rare in my collection. The aforementioned Firefly cards have a lot of care put into the card faces. Every card has a slightly different stain, whether it's blood, grease or something else. (I really don't like it when cards are "worn" but every card has the exact same wear pattern) If the cards are going to be standard, I like it when the coloration is different (and matches the overall look of the deck). I like how the Citizens deck has slightly darker reds, and the metallic ink highlights on the court cards really make them pop. I really like the version 2 Bicycle Denim deck, with how the pips and court cards look slightly worn and faded, like they were ironed onto the jean material, and how the Ace of Spades looks like it was a leather patch sewn onto the denim.
* Readability. Above all else, a deck has to be functional for me. I don't mind if the reds get changed to another color, but diamonds and hearts must be the same color, and the clubs and spades must be a different color. There's a deck called The Olympians that was on Kickstarter, and it looked amazing, down to the book-like tuck box...but they made the spades and hearts gold, and the clubs and diamonds grey. That was a deal-breaker for me.
