The Xeon is the stronger CPU, R9 390 and GTX970 are very similar in performance and they work equally well with both AMD and Intel CPU's so no need to select AMD with AMD or Nvidia with Intel. You can mix any way you want.
The 9590 isn't worth considering, it's a pre OCed 8350 that needs twice the wattage, a bare bone 4770 is a better CPU, so go with the Xeon or get a 4770K, 4790K or the like
The Xeon is the stronger CPU, R9 390 and GTX970 are very similar in performance and they work equally well with both AMD and Intel CPU's so no need to select AMD with AMD or Nvidia with Intel. You can mix any way you want.