Let's first get the ugliness out of the way. AMD and its drivers seem to be broken currently in Island 359 with both the AMD R9 Fury X and RX 480. Given that we saw no scaling at all with the RX 480, no matter what IQ settings we used, the performance just does not seem correct. There is no way we can suggest you buy an AMD GPU to play Island 359 at this time. I would expect to see better performance in this game if, or rather when, AMD gets its driver team paying more attention to VR gaming. There seems to be a huge discrepancy between resources being allocated by AMD and NVIDIA when it comes to actual VR gaming consumption.
Moving to the GTX 1060, we saw better performance, but not enough to give you the gaming experience you will be wanting in a game like this. Yes, the GTX 1060 will get you to solid non-Reprojection play in Island 359, but as I discussed above, "Low" IQ is not likely going to give you the gaming experience you desire. I consider the GTX 1060 truly an entry-point VR product for GPU-intensive titles and it shows to be just that today.
The GTX 1070 is the sweetspot when it comes to Island 359. It will get you to the level of image quality and gameplay I think you would greatly benefit from in this game. It pushes the edge of the Reprojection envelope, but just close enough so as to not be an immersion-killing distraction.
The GTX 1080 and TITAN X Pascal GPUs are more than enough to play at Medium IQ and easily have enough performance to allow you to scale up Island 359's IQ knobs, sliders, and presets as you see fit. To that point, this game gives you a plethora of IQ settings to adjust to your preference as well, which is something I would like to give big kudos to CloudGate Studio for doing. Island 359 is truly being held back by the HMD hardware rather than your video card, and that is something that will surely evolve in the future.
http://www.hardocp.com/article/2016/09/01/amd_nvidia_gpu_vr_performance_island_359/6#.V8hmTq2XolA