The perfect gfx card for a i7-8700K sitting on a ROG motherboard would probably not be anything as mid-range (ish) as a GTX 1050 Ti. That is a high end platform you have that begs for a high end card and gaming at high rez and high refresh rates.
But if you're trying to keep the system all-Asus, the the Stryx line is a good choice.
If you still need a PSU, you won't go wrong with almost any Seasonic.