I haven't purchase an AMD reference board before so apologies if this is a dumb question. From what you said it sounds like all reference boards are made by the same manufacturer so it doesn't matter which board partner you get one from, the only difference is likely to be the box and label?
While technically true, Asus, MSI and Gigabyte will mark theirs up higher, with Asus being the worst offender.
Yes you will actually pay Asus more for the exact same card as all the other vendors, but you gain so much with their absolutely horrendous customer support, so i guess the Asus sticker is worth more than the other vendors lmao.