Prospective build:
CPU: Intel Core i5-6600K 3.5GHz Quad-Core Processor ($233.99 @ SuperBiiz)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($24.33 @ OutletPC)
Motherboard: Asus Z170-A ATX LGA1151 Motherboard ($145.99 @ B&H)
Memory: G.Skill Ripjaws V Series 16GB (2 x 8GB) DDR4-3000 Memory ($94.99 @ Newegg)
Storage: Kingston SSDNow V300 Series 240GB 2.5" Solid State Drive ($64.89 @ OutletPC)
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($53.00 @ Amazon)
Case: Corsair 200R ATX Mid Tower Case ($49.99 @ Micro Center)
Power Supply: EVGA 600B 600W 80+ Bronze Certified ATX Power Supply ($49.99 @ Amazon)
Operating System: Microsoft Windows 10 Home OEM (64-bit) ($79.89 @ OutletPC)
Monitor: AOC G2460PG 144Hz 24.0" Monitor ($350.98 @ Newegg)
Total: $1148.04
Will be making the build when I return from Abu Dhabi in a few weeks. Will wait to see what happens with the Pascal cards before adding. Questions I have are 6600k vs 6700k, are cheaper Mobo's ok, and the monitor (I keep going back and forth between this and the Dell - I feel reasonably comfortable with the G2460PG, though).
$1200 is the limit pre-GPU, including Windows and Monitor. I've been debating going to the 6700k by cutting some costs elsewhere - maybe with the MOBO and a smaller SSD.
A 'cheap' z170 board shouldn't perform worse than a premium 300€+ one. Of course there are still differences in design (if you care about stuff like that) and equipment like number of sata ports, number/generation of usb connectors, sound chip quality, wi fi, lan port, PCI-e slots, cross fire/sli capability, extra fan connectors/controllers etc. In the end it's up to you to decide what you need.
About your CPU decision. I upgraded last week and I thought a lot about the i7 vs. I5 topic. In the end I went for the i7 for longevity reason. Normally I'm upgrading my CPU every 3-4 years and I'm always trying to get something that is able to hold out that long.
I bought my last CPU (i5 3570k) when most games weren't even utilizing 4 threads equally or at all, so an i7 seemed to be a bit overkill back then and the i5 seemed like a cpu with some headroom for the future. Today CPUs able to handle 4 threads are the bare minimum as some games even refuse to start on a 2 core cpus without HTT. So I decided to go for a 4 core CPU with HTT this time around (fully aware that 4 cores + HTT aren't as good as a true 4+ core CPU).
Any real reason for the sound card? Onboard is pretty good nowadays.
Also this.
@Igo: I'm using the asus z170 a and the sound quality is surprisingly good.