I only do a build about once every 8 years these days and for me I had just not heard of Asrock. I do a bit of research when I do a build but I'm far from a hobbyist.
I'll definitely look them up next time because I've had issues with a relatively expensive Asus board in the past.
They're not gamerfied to the extreme, and they don't cater seriously to Western aesthetics.
ASRock are just solid, dependable boards with good design and great firmware. They segment for all ranges of computing so you have to know a little bit about what you're buying before you pick one, because spending the most money won't necessarily net you the best hardware for your task.
They're bigger in SEAsian markets, and I end up searching Chinese and Japanese blogs when I'm looking for substantive post-sales information.
I'll definitely look them up next time because I've had issues with a relatively expensive Asus board in the past.