The GTX 970 listed above would be a great choice for 1080p gaming. If you're looking to perhaps go up to 1440p the R9 390 would be another very good choice for almost the same price:
Video Card:MSI Radeon R9 390 8GB Video Card ($309.98 @ SuperBiiz) Total: $309.98 Prices include shipping, taxes, and discounts when available Generated by PCPartPicker 2015-11-23 11:00 EST-0500
Although if you're gaming at 1080p, then ak47jar3d's suggestion, probably just tops the 390 at that resolution. Although, my suggestion is $20 cheaper, so swings and roundabouts.