zotac makes crap, I don't know where you heard that they are the best. I would say EVGA is the best company because after all you have to base it off of customer services too. If the card dies, who will pick up the bill? If its in warranty EVGA will take the card no questions asked and give you a newer card.
If you are talking about out of the box performance, the 980 Ti is limited to around 1500mhz~ core clock so it doesn't matter what card you have unless your going LN2 or Water cooling.
Lastly, you can buy 2 used 980 Ti on ebay for $500 each, or 3x 980s for $1000. I personally have bought 4 980s at different times for $350-400 each.