Quick ramble about mine.....
Using auto settings, the system was stable and didn't overheat at 5Ghz across all six cores with Prime95 @ 100%.
But other than bragging rights I don't really need an overclock and the voltage was higher than I was comfortable with - so it's back at defaults.
I was quite happy (and surprised TBH) to see Intel had made a bit of extra effort and included these two little cards inside the CPU pouch:
For RAM I never get high end stuff - I've always found memory speed upgrades to be the most depressing way to spend money - so it's just 2 x 8GB G-Skill at 2666Mhz CL15.
For cooling I didn't feel like mounting a big air cooler this time around, and I've never been completely comfortable with that much weight on the motherboard when a system is being moved around - especially when they get older and get shunted a bit. So for the first time ever, I tried an AIO, I went with the CoolerMaster ML240L - it's a thin 240mm radiator with dual fans - thin is important because I wanted a top mount and most cases don't have enough space for top coolers to clear the RAM.
For video I went with a Gigabyte GTX1080, despite it being a brand I said I'd never buy again. In this case it was a factory second that'd been fixed up, and was selling for GTX1070 prices in it's original box - it works great. Barely gets warm, the only time I've heard the fans spin up was when I did it manually with the controller.
I also have a PCI-E USB 3.0 adapter in the back.
Case I went with the Fractal Design Meshify C - with the exception of lacking a USB-C header, and less mechanical HDD mounting room than I'd like, it ticked all the other boxes - such as a top mount radiator + tempered glass + hidden PSU etc. I really like the dark tinted glass because I wanted to do LED lighting, but didn't want it to be the usual super bright wow-fest and I think the dark glass helps keep things a bit more subtle.
I know it's "cool to hate" on RGB lighting, but I quite like it.
Thankfully the Gigabyte video card has no lighting, so with the dark glass I don't even see their logo when using it
Windows 10 fixed itself (I did not install fresh) and booted to desktop (used the same install I had on my old Asus Z170AR + i7 6700K setup - which will now be sold off for parts).
For storage I have a 500GB Samsung 970 Pro on the motherboard with M.2, a 250GB Samsung 850 (or 840?) SSD hidden away for my games library, and a 2TB WD Red for storing video files. Transferring my system from the old Samsung to the new M.2 drive was super easy with Samsung's Data Migration tool.
System boots Windows 10 faster than it can do it's own POST routine.
EDIT: As for Z370 + CPU - it's the same as any other generic six core build really - I have enough PCI-E lanes for what I do and it works and it's pretty brisk.
Asrock Gaming K6 has a serial port, PS2 ports, VGA - which I thought were interesting gamer choices? And were one of the only companies to bother redesigning their power delivery for the new slightly modified socket design (AFAIK) in the mid-range market - so that's why they got my vote. Would have preferred more USB connectors on the back, and more on the case, but we can't have it all I guess.
EDIT: One big issue was that most motherboards in stock here in NZ had not had the BIOS updated and thus did not support the i7 8086K - I ended up having to pay someone else to slap a new i3 in it and do the update. Very annoying!