Single 980 >= 2 960s in SLI.
2 980s in SLI > Single 980ti
I would suggest you to get the single 980ti cause it's cheaper than the other solution and GPU scaling in most games would be better than 2 980s in SLI.
In CPU you have two choices either 4790k or 6700k, you can save some money by going the 4790k route cause you don't have to upgrade your ddr3 ram, in other case you have to buy ddr4 ram. There is only 10-12% performance difference between the two.