If you are planning on overclocking you want the Z170. If your only requirements are that it can run an i5-6600K, do overclocking, and support a GTX 1070 then the boards are all literally the same for your purposes. Pick one at random, you'll be fine.
If you aren't, then I suggest an i5-6600 (non-K) and an H170 board - you can configure the chipset on the search page there. Again, if all you need is an LGA1151 socket and a PCIe x16 slot you can go ahead and pick one at random. They're even more similar since their overclocking abilities don't even exist so we can't even compare or wonder about that.