each deck is quite different... As far as looks, neither deck has really gotten any recations from people (unlike the Tiger deck which usually catches people's eyes). I personally like the SS back as they're really nice and subtle in how they look.
As far as feel, each feels quite different. The SS cards are thin and bend easily while the Guardians feel thick and stiff. It's more of a personal choice to which one is better as they both feel good in their own way. Personally, I like the guardians more, but a double lift with the SS feels insanely good because of the thinness and grip on the edges.