I didn't look at both games. I was pretty convinced by the game mechanics of TWD upon trying it at an event and I love Robert Kirkman's walker IP.
You have generic Zombies in so many games now. Even
Spoiler (click to reveal)
is essentially a zombie virus. And Kirkman's idea that the Zombies are really a penalty to everything in a world that pits humans against humans and not this idealized holywood human vs. zombies scenario, this idea that it is the survivors and not the zombies, who are really the walking dead, is captured beautifully in the game.
The only Zombie game I ever liked as much was Dead of Winter. And that one is not really about Zombies either.