If you want raw power, get 2x 980s. If you want a single GPU solution without worrying about SLI issues or if a game will support SLI, get the Titan X. All you'll have to do is OC the Titan X to get the performance pretty close to 980 SLI. If you play quite a bit of older games, which some might not support SLI, you're better off getting the Titan X so you'll have a strong single GPU performance to get constant 60 fps. If you have a g sync monitor, that would be even better to pair with the Titan X.