Motherboard Help

Uhhh.

They score about the same in reviews it seems. Gigabyte has "bad" wifi, Asus also has "bad" wifi and forgot to add more RGB LEDS to the board...
So really go through the feature list and figure out what you need. Without more details about the rest of the computer...all we can do is guess...

Go with Asus

Brand with your GPU if u using Gigabyte pick gigabyte - if you use asus pick asus

I think Gigabyte has better customer support, may be worth considering. I recently had to RMA my Asus mobo and they wouldn't do an advanced replacement, which is pretty necessary for a mobo.

Do you need wi-fi in a desktop board?
If no, then I don't know why don't you pick the ASRock Z370 Extreme4. Quite cheaper, has more SATA and USB3 ports.

8700k is oc capability cpu, so you should dig on the internet which mobo has better oc performance. Then you can choose the good one if you will oc. But mostly Asus has better support to oc. If you wanna glowing mobo then you should go to Gigabyte.