Hello, if you are doing a lot of design work, I recommend that you get a CPU with a high core clock (the amount of cores is slightly less important). You would be better off spending more money of your budget on a decent CPU, and lots of RAM (if you haven't already), and saving a little money on the GPU (some design processes are less GPU heavy).
From this site you can see their comparison of the best CPU's for graphic
In this article, they recommend Nvidia GTX 1050 or better a GTX 1060 which will keep your PC performing well for a long time.