Based on the price of the parts you listed you generally can't go wrong with the GTX 1050(ti) or GTX 1060 3GB/6GB. If those GPUs aren't your taste then more information on what you want (e.g. resolution and fps target) will help in choosing a GPU. The GTX 1060 can run most games over 1080p60fps on ultra settings and even more fps on lower settings. The GTX 1070 should be able to do 1080p144fps and even 1440p60fps at ultra settings and even more on lower settings.