I see an i7 6700k for 220 dlls, I think is a good price but checking benchmarks it seems i5 8600k is better but also a little bit more expensive. Currently I have an i3 6100 an a B150 motherboard.
The i7-6700K will offer you very simliar performance, but you cannot overclock it on the B150 mobo. So overclocking would be a reason to upgrade to the Z370 platform.