The 780 ti will be better. The 970 replaced the 780, and the 980 replaced the 780 ti.
Here is the 780 ti with the 980 in Metro Last Light at 1080p
Here is the 7780 with the 970 in Metro Last Light at 1080p
If you decide to go with EVGA's "FTW" edition, the 970 will be faster in some games.