I would highly recommend picking up the GTX 970 instead of any of those other GPUs. The 970 is the current dominator in price-performance, being priced at $350 and competing with the 780 Ti in several benchmarks, as seen here- http://www.videocardbenchmark.net/gpu.php?gpu=GeForce+GTX+970&id=2954.
In all honesty, I see little point with going with the GTX 980 over the 970 for $200 more, just as I see no point going with the Titan over the 780 Ti. SLI 970s can run all games 60FPS+, at least from what I've heard and using, even on up to 4K resolutions, as seen here- http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_970_SLI/7.html.
And keep in mind, you can almost buy 2 GTX 970s for the price of a single GTX 980, so if you must spend over $500 on your GPU, buy the SLI 970s, you won't regret it.