A 980 will win in performance with 100+ MHz higher clock speeds, better overclocking, lower power consumption and TDP, and it also has more VRAM. The 780 Ti is, for some base line models, ~$100 cheaper though. As for what brand I recommend if you ever plan on water cooling go with an EVGA, because of their reference PCBs. Otherwise the decision is up to you, Gigabyte does offer the highest clock speeds, and some of the best temperatures with their windforce cooler though.