If someone could tell me just the best one - that's what SevenStars did - just sort of unofficially, off the record - I just tend to go with that one.
Le Fanu: "Best" is so subjective! I put the thing together and I don't have a favorite. There are bits of each one that I like. I personally like the bordered version, because after all I designed the border and did a little more work on the cards, so it's just a little more "mine" -- but also that much less authentic.
But I think my favorite card back is the one that comes standard with the basic version -- the marbled green. The printers just do a wonderful job with it.
I understand the feeling, though, of being overwhelmed by choices. I sometimes wonder if it would be better to just offer one version. I'm sure you're not alone.
DT