I know this can be an aggressively contested subject, and without wanting to start that kind of thing, I note the Gigabyte Z170X-Gaming 7 has both Intel and Realtek Killer NIC Ethernet sockets, yet the Z170X-UD5 has two Intel Ethernet sockets. What would be the benefit of having the Killer NIC over two Intel that support Teaming (whatever that quite is).
I was originally thinking why 2 Ethernet sockets??? But now, I can see the point if running a Virtual Machine and using one Ethernet purely for the VM using something like a bridge setting or something, kind of isolating the VM and it's networking from the main system almost entirely. I suppose it could have some use in gaming where it may reduce latency or something too, perhaps.
For me the look of the board is completely irrelevant. Actually, every component's aesthetics are of no concern to me, as they're going in a non-windowed case, only the outside of the case matters in looks. However, I am looking for all the little things that make it easier to put together and keep clean, and keep running well with good ventilation around all parts. Things like easily placed front audio headers and such, non-cramped component layout etc.
I do have these two the Gigabyte Z170X-Gaming 7 and Z170X-UD5 in the short list, with the favour to the Gaming 7 because of better audio but they are pretty close to each other.