Motherboard, Quality, Reliability, Bios

This is gonna be answered subjectively based on everyone's experience and preferences, lets be real.

The Fatal1ty range is not "just hyped up overpriced." What you're seeing ASRock do on X299 and now X370 is offering a Taichi model and then basically adding a 10Gbps network adapter and a different color scheme and branding it Fatal1ty. That's the main difference between those two boards. Go price out a single 10Gbps copper PCIe network adapter (X540-T1...) and you'll understand why that alone justifies the price difference between the two boards.

ASRock always has and continues to make great boards. I use them in my personal and professional builds for the simple reason that they give you a huge feature set for the price compared to other manufacturers. They also don't constantly share on-board resources with other ports, which Asus is infamous for. You find yourself constantly disabling some port by connecting hardware to some other port. Yes, ASRock still does this but not nearly as bad as other manufacturers I've seen. This issue also becomes less and less an issue as CPUs and especially chipsets keep offering more resources to hardware every new release.

You're seeing other boards that cost more than ASRock variants for what seems like only because they light up more with LEDs. That's fine, as long as its worth it to you.

ASrock also tends to differentiate themselves with power phases in similarly priced mobos from other manufacturers, which draws in overclockers.

At the end of the day, different people hold different allegiances to different manufacturers due to years of use or just maybe a bad experience. Every single time I give Asus another shot I get disappointed. That said, for the most advanced OC'ing they're great if you want to tinker with every single tiny setting you can for OC'ing. I built on a Gigabyte X99 board a few months ago and while it was hands down the prettiest board I've built on but their BIOS is miserable. I built on a few EVGA X99 boards (classified and FTW) and really do like EVGA, and the BIOS, but I was always missing some little thing that ASRock would have given me. I've built around 30 machines in the last couple years on ASRock boards between X99 and X299 and they're great. Never even had a DOA board, and these are in intense use cases on 24x7 with customers.