You really can't go wrong with any 290x/390/390x or 970/980.
Here is a recent review, only a couple months old between a 290x and a 970. As you can see, with current drivers, at 1440p, they're very close:
http://www.hardwareheaven.com/2015/06/evga-geforce-gtx-970-review-ssc-edition/
I...