As always, 4K puts forward a more serious challenge for GPUs. Here the R9 380 and GTX 960 averaged around 30fps, which I would call unplayable in this title. Even the GTX 970 provides a bit of a rough experience here at 45fps while the R9 390 was slightly better at 50fps.
The cheapest way for gamers to reach that magic 60fps is the R9 Nano. The new $600 GTX 1080 (from board partners) performed admirably with an average of 91fps and this means the card will still be able to deliver over 60fps using the epic quality setting.