>>3971197First. Disregard everything that anons above me said.
Second. Photoshop painting needs strong single core performance and is optimized for intel. So current ryzen CPU's are out. Not sure how new ryzen3000 will behave, but my guess is Intel will still be better because of optimization.
I recently upgraded my very old AMD pc to the used 3d gen Intel core i5 3570k(4 core 4 threads) for pennies, overclocked it very mildly to 4ghz(it can go up to 5ghz easy, but you'd need a good cooling) and the performance increase is amazing.
So, you don't need a lot of cores. You need an intel CPU with strong single core performance. I can whip out a build for you that fits your budget if you tell me what your budget is.