Both the Asus Z170-A and the Z170 Pro Gaming seem to be by far the best Z170 mainboards for my needs. They have all four display connectors (VGA, DVI, HDMI, DP), and with a compact arrangement (unlike the weird space-wasting ASRock does with Z170).
Also, they have digital audio, and 6 / 8 external USB connectors.
Differences:
Z170-A:
+ low DPC latency (
according to this AnandTech review)
+ low power consumption
+ beautiful design
~ 2 PCI slots for legacy
− simpler integrated audio (possibly worse sound)
− 2 USB connectors less than Pro Gaming
Z170 Pro Gaming:
+ newer integrated audio with added amplifier (on the flipside, this might cause higher DPC latency?)
+ 8 instead of 6 external USB connectors
~ no legacy PCI, but
~− DPC latency not known (no proper reviews yet)
− also tends to have lower user rates on listing sites than Z170-A (A: 95% of 44 positive, Pro Gaming: 55% of 11 positive on geizhals.at)
Makes it seem that opting for Pro Gaming is a bit more risky. It’d be great if we got a review from AnandTech on it.