Like with everything it depends… Simple decks like the one you are showing, or red dots for example, are a bit to minimalistic for me. But there are others that I really like (cherrys or 1st epc by chris ramsey for example).
Simplicity is awesome but it has to be above a certain threshold.
With detailed art its pretty much the same. There is a point where you can “overdo” it. Buuuut I think in general I tend to find detailed cardbacks more interesting.
I would echo what Acixcube says. As a magician my farite Back is the Bicycle Paris with the Rider, Maiden, and Mandolin right up there too. I don’t want the spectator to be concentrating on some strange look of the cards. I want them to concentrate only on the “magic”. OTOH I love the designs like the Cherry Decks. And the new Organic Playing Cards Peelers and new Oranges Deck are fun and cool. I also like bright, clean geometric designs. I think black is overused and no longer cool. I’m also very tired of cards that have a “dark” or “horror” theme. And I think Knights and their like are getting old.