1080ti, because of power cost, efficiency, and selling that 1080 before it becomes too old, but I'd just wait for the 1180 or whatever it will be named instead
Nvidia never announced anything this year at CES so I wouldn't hold out much hope of them releasing anything soon, they have always in the past at least mentioned the next line or in the past couple fo years fully discussed it at CES with a mid year release but this year we've heard nothing not even proper rumours.
With Amd Vega being such a let down Nvidia don't seem pressured to push anything through.