980ti is the best for the money. It is basically the Titan X with 6gb VRAM less, which isnt too useful right now anyways. The 980 isnt worth the premium over the 970, so its basically a waste of money.

I would get the 980ti.

980Ti all the way
it's the Titan X's little brother who also goes to the gym every day. Half the price of Titan X, 5 FPS difference between them.

Depends on what resolution you're gaming at? If its 1080p then none.

980Ti typically out-performs the Titan X in games, because you'll most likely go with an aftermarket cooler, instead of reference, so temps will be better with the 980Ti, and you won't get throttling. The extra 6GB VRAM literally does nothing for the Titan X in games. 980 isn't worth the premium over a 970, so instead of a 980, you should be getting a 390.

980Ti would be an aight choice, but check out the Fury. You can unlock the cores on a Fury and turn it in to a Fury X. I've seen someone buy a Fury, unlock it to a Fury X, and then overclock it. They managed to double the memory speed from 500MHz to 1000MHz, which means the memory bandwidth on their card was 1024gb/s, or 1tb/s, which is absolutely insane, especially when you consider the 970's bandwidth is about 220gb/s, and the 980Ti's bandwidth is something like 350gb/s.