GTX 1060 6GB would be plenty for 1080p for current games. A CF RX 480 would have two cards, cost twice as much, perform better in most games but some games won't support CF. Realistically dual RX 480s vs single GTX 1060 is a different budget. If you'd add the second card later on, my advice is don't bother and just get the 1060. By the time you have enough reason to upgrade to CF RX 480s, there will be a better GPU out there and you could sell the RX 480 and upgrade to it to get better performance in *all* games. Meanwhile, RX 480s will be harder to find and you really should have two identical cards (down to the VGA BIOS).
Thank you so much
The most common mistake in gaming PC builds is "I'll SLI/CF later on." No, you probably won't.