780 Ti all the way.
A 780 Ti at stock would kill even the highly overclocked 780 any time of the day. Also since you are getting it for cheaper than the 780, then this is awesome. Just blindly go for the 780 Ti.
If anyone recommends the 780 over the 780 Ti, then ignore that person completely. He might not be knowing that what he is talking about.
Buying a more powerful card for cheaper makes the most sense and would also give better performance. So, definitely get the Palit 780 Ti any time of the day.
Have fun gaming with your new 780 Ti, the best Single GPU card in the world