what should i get the GTX 780ti or the GTX 970?

The 980 is actually cheaper. You can get one for $550 whereas the 780ti is in the $590+ ballpark. Yeah it'd be nice if the 980 were a bigger leap in performance, but the main draw of the 900 series are their incredible reduction in watt usage, which generates less heat and means more stable performance (and possibly higher overclocks). Don't get me wrong, raw performance is the big thing to pay attention to, but don't forget that there are other variables you might want to consider.

You also get one more gigabyte of VRAM for far less the cost of an equivalent 780ti. More than 2GB of VRAM isn't terribly important, but it doesn't hurt to have it in the long run. Up to you! But my opinion would be to go for either one of the 900 series cards.

(Edit: Saw you using euros in another post. Sorry, not sure of the cost of the cards in that currency!)

The 780 Ti is a beast. So how exactly are you not happy to have a card that's even somewhat faster than that?

Wait a bit for the prices to settle. The 980 is really in the same price-range as the 780 Ti. NVidia will not drop the price on the 780 Ti any further. They will simply discontinue it, since it's expensive to produce. 780 Ti, 780 and 770 are all getting discontinued. If you can find some vendor who wants to get rid of their stock and find a cheaper than usual 780 Ti, then of course go for it. But otherwise, 980 and 780 Ti are comparable in price, so it doesn't make much sense to not get a 980 instead.

Also, the 970 is very good too. It's about the same performance as a 780 (which was a very fast card) but is cheaper.