Really depends on what you need it for. The 2 cpus are very comparable. On one hand you have the 7700k which is a 4 core 8 thread machine that runs a base speed of 4.3ghz. The 8700k runs 6 cores and 12 threads at a base clock speed of 3.7ghz. The 7700k is a 91 watt chip while the 8700 is a 95 watt chip. The 7700 is 300 dollars and the 8700 is 400 dollars speaking on a mathematical bias the 8700 will give you more bang for your buck. Personally I'm an amd fanboy.