ECS is an OEM manufacturer that happens to have put its label on it's line of retail products, meaning that ECS builds motherboards, among other components, for other brands which you have probably heard of but for several years now, they've been releasing their own branded products.
They're generally reference designs but they do have a handful of unique ones. They used to be cheaper than everyone else but as they've become more and more accepted as a mainstream manufacturer, their prices have started to get closer to the "tier 1" manufacturers like Asus and Gigabyte.
I've used ECS motherboards many times in the past and problem rates have been no different than any other tier 1 manufacturer. I'm talking maybe 20-30 motherboards over the last decade so sample size isn't exactly scientific.