And then there's this to consider. The GTX 980TI was WAY overkill for 1080p, even with max settings, on everything except Witcher 3, when it was released. After they made a few months worth of optimized changes to Witcher 3, it was more than enough for that even on Ultra settings.
Now, it still works on 1080p Ultra with most game titles, but the hardware requirements have gone up due to advances in game technology, and it's definitely NOT overkill anymore. So even if you get the 1070 ONLY for 1080p, even if it's a little bit overkill now, the titles that come out in one or two years may seriously change that and you'll be glad you went overboard rather than wishing you'd just spent a bit more for a better card.
Personally, I think the hundred dollar difference between the GTX 1070 and GTX 1080 makes it more than worth it to go for the 1080 considering with that you'll be good at 1440p for a good long while. But of course it's another 100 to 200 bucks depending on which model (Dual fan aftermarket models only) you are looking at.
If you really want 1440p, you have to decide how much you can live without when it comes to in game settings and kind of let that be your guide.
For me, high settings at 1080p are good enough for now but when I make a move to a new gaming hardware setup I'll definitely be looking at 1440p at max settings, and I want it to stay that way for a while, so I'll wait and jump on a 1080TI when prices come down along with a decent 1440p G-sync IPS panel. I expect that to happen in the next six months or so and last me probably four or five years.
Are you wanting an IPS panel or can you live with a good 1440p TN panel? Obviously TN is a lot cheaper, but there are some pretty reasonably priced units that offer both.
This is probably about the best 27" IPS 1440p monitor that is suitable for gaming and isn't ridiculously expensive. With a 4ms resonse time and a really good panel, it's probably going to be my next monitor as well.
PCPartPicker part list /
Price breakdown by merchant
Monitor: AOC - Q2781PQ 27.0" 2560x1440 60Hz Monitor ($339.99 @ Best Buy)
Total: $339.99
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-11-06 00:32 EST-0500
It also got rave reviews here at Tom's and a lot of other sites as well.
http://www.tomshardware.com/reviews/aoc-q2781pq-ips-qhd-monitor,5068-6.html