It's a tough call. Both great pins. GOT has pretty cool rules. But you really need to scratch at them for a while to get the strategy down. Once you understand them, it can really shine. TWD is just different. The layout, and (on the pro) sweeping ramps that if you miss, you're hamburger. I've heard the tilt warning sound on TWD more than any other game. You are always fighting the game. And the rules fit this nasty fight very well.
Both are quite unique, but I'll lean just a bit towards TWD.