If you're not going to use Cuda support, which can be fast but very troublesome, the i7-6700k or i7-8700k are pretty amazing at video encoding and decoding, and make PS18 and later a breeze to use.  The 8700 adds h.265 encoding for 4k video exporting.  Otherwise they are basically the same because even though the 8700 is faster, it slows down when the GPU is being used.