B550 would make perfect sense. Actually good VRMs with PCIe 4 NVMe slot and PCIe 3 graphics, so to not overprice it.
You don’t need 300$ board for the 150$ processor… So a 100$ B550 board with limited PCIe 4 support may be just fine.
To answer your question:
A - low end, office work, poor feature set, no OC.
B - average feature set, nothing impressive but generally well rounded, some OC.
X - high end full OC support, rich feature set.
The chipsets B and X themselves are about the same, so unless you need some super high end features B can be just fine.
300 is the first generation, 400 is polished second generation and 500 is the PCIe 4 supported latest generation.
Because back at Ryzen 1 AMD, company on the verge of bankruptcy, comes out with this amazing new technology, while slumbering in the last few years with nothing. The board partners have them.some support though, much better support than what was happening with the FM2/FM2+…
Back at 300 series boards everything was meh. There was the crazy TaiChi and the super high end Asus board and everything else was meh…
400 series comes out and sales price not to be so bad, so we now have some decent boards on the X470 platform. B450 with their up to 100$ pricing was just OK with nothing amazing. But now they know it sells. There is a reason to put an effort and charge for the effort… There are some good X470 boards, but they have the price tag to show for it…
Were you expecting cheap great boards? Did intel ever had cheap great boards? I kinda miss the logic here…
¨Cheap and great¨ is simply not really a thing.
In the end producing a motherboard costs money.
Price cuts for cheaper boards are most made in the connectivity and vrm department.
And yeah in my opinion cheap out on a motherboard is never really a good idea.
Unless there is truly no budget room.
But still i see it many often people buy a 3900X and the cheapest pile of shit,
motherboard they can find.
And that is never really a good idea in my opinion.