dublicate, dont answer

Both GPU's perform the same, only if you are running benchmarks you will sometimes see a slightly better framerate with a GTX 1060 6gb, or sometimes the RX comes out on top. It is not a noticeable difference, they perform very similar.

Since you have a 4k screen with freesync, the obvious choice would be the RX 480 8gb. It will perform (slightly) better at 4k since it has more memory, and on top of that it supports freesync. Nvidia GPU's do not support freesync, only their own gsync. Keep in mind though that neither GPU would perform very well at 4k, you would have to play at medium/high settings and tune the settings to get good performance at 4k.
 


Will freesync function work in 1080p or 1440p or only in 4K resolution?