If that's the game you play and you know the 960 can do it on ultra then get the 960. No point getting the 970 just because it's more powerful. Remember this is toms, people will usually point you towards the more expensive/higher performing thing just because.
Want to play lol or dota? Well obviously you need sli 970s. I'm kidding only slightly. You will get people telling you to get more than you need cause you MIGHT want to possibly do something else one day maybe.