Thats a strange comparison. If you dont care about price get a 980 ti. The 690 is a duel gpu card it might perform a bit better than a single 970 but i would still rather have a 970 you wont have any of the pitfalls of sli, it will use far less power, and make far less heat. And unless you buy the 690 used its far more expensive than a 970.
Well, i am planning to buy a computer. One have a gtx970 and one have a gtx690, that is why i did not care about price since both computers costs the same. But thanks for the answer, think I will buy the one with a 970 then.