Questions and looking for AM4 motherboard recommendations

So it's finally time to replace my 2500K. I plan on grabbing a 3600X or 3700X next month. I don't really see the value of a X570 board as they appear to be significantly more expensive than a B450 or X470 board and I don't plan on getting a pcie 4.0 SSD any time soon.

So first, X470 or B450? I don't really ever plan on running SLI or Crossfire ever again so that's not needed. Overclock support is probably top priority.

Second, brand? I really don't want to ever buy another ASUS product but if they offer what I need then let me know.

Third, overclocking? I've read a lot about phases and chokes and some boards will say X number of phases and then reviews will call shenanigans. I will be cooling whatever CPU I end up with under my custom loop and would like to get the most out of it OC-wise. Obviously we don't know how next gen Ryzen will OC, but I would like my board to be ready for it.

Fourth, are current boards shipping with a BIOS that will run next gen Ryzen? I don't have a current gen Ryzen chip so I need the board to either come with either a newer BIOS or allow a BIOS update independently.

An ATX board is preferred just because it will fill up my case better, but mATX would work as well. 4 RAM slots would be nice as I will probably start out at 2x8GB and upgrade later on.

Budget: around $100 would be nice but up to $140 is fine if there is some big improvement.

With that budget you probably want to get the MSI B450 Pro Carbon, or possibly the Tomahawk but you might be slightly more limited on overclocking. We don't yet know what sort of power curve you get from overclocking Ryzen 3000, so anything is a guess right now. The idea boards for pushing the clocks hard are the better X470's but they start over your budget.

The 3000 support BIOS just came out, so if you're an early buyer you'll either have to work with your retailer to ensure an update, or borrow/buy a cheap CPU like a Ryzen 1200 and use that to update.