There will not be an appreciable difference between makes - a few Hz difference in clock speed will not be noticeable in practice so go with which ever one you like the look of and is the lowest price or has the longest warranty. I have run eVGA and ASUS in the past and both work well . . . . . . but you don't really need a GTX980Ti to game at 1080p. A GTX970 will cope more than adequately with anything at 1080p. My GTX970 Strix overclocks like a champ but again once you're running in the hundreds of FPS then a few more FPS is not detectable by the eye.
If you are going to game in QHD (2560 x 1440) then its worth splurging on a 980Ti. That being said the new Nvidia models will be on sale in a couple of weeks and will invariably offer more performance for the same $ so I'd wait and pick up one of the new cards . . . or if the price of the old ones drops, which it usually will, then pick one up at a discount price.