If you need card right now and no money for TITAN X only right option for you will be GTX980 SC, GTX980 Classified.
I would advice you GTX980 SC reference design but much better Classified model.
You will not see any improvements with GTX970...
Buying another 780 is bad option too because limited memory.
Example Dying Light is one nice game but need more video memory than 3GB.
Except that 780-780Ti cards are good for gaming.
It's stupid to install SLI and only because memory to drop texture on medium in more and more games... 
From 780 to 980 you will have more fps improvements than 780 to 780Ti.  That's nice upgrade.
First colder card and more space for OC, low power consumption I will not count because that's less important thing, but 1GB more video memory is exactly what few games demand for max settings and difference in GPU is about 30% because 780 is not full chip and 980 is even stronger than 780Ti. You can sell your card and invest in 980, best option.
 

Off course if GTX980Ti is full GM200.
 

beekermartin
I know moving to a 970 is not really an upgrade.  I just figured now was the best time to sell the 780 and get the most money for it.  The 970 should perform about the same as the 780 but be a bit more future proof.  3.5gb ram, lower power consumption, etc.   
 
It sounds like it isn't worth the hassle of selling the 780 and the two games that come with the 970.  I guess I will just keep the 780 Classified for a bit longer. 

Good decision. I'm in a similar mini-predicament since I am running 2x 780 Ti's. I find it very funny that people always said your GPU will run out of power before vram will become an issue. Well, SLI 780 Ti are more than capable of maxing out games at 1200p / 1440p but for the vram limitation. I wouldn't do a thing until we know what exactly is coming from AMD and nVidia.
 
*Edit- just saw that the 980 Ti will launch next week, sweet! Don't like the rumored gimped CUDA cores compared to Titan X, though.