I would rank them Gigabyte, ASUS aclose second, MSI, then ECS last.
I think Gigabyte boards are a little better than ASUS, but I have to admit that the evidence is largely anecdotal. I know that, with older ASUS boards, you need to go in and physically clear the CMOS if an overclocking setting doesn't work. Don't know about the newer ones. Gigabyte boards will try to boot, and then, if they fail, reset themselves to a bootable configuration.
No experience with MSI boards. ECS tends to make basic, no frills motherboards.
I mostly build with Gigabyte boards. I used an ECS board in my desktop at work. It was more than worth every penny. Got it free as part of a package deal at Fry's.
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Building computers since 1977.