The motherboard price argument is quite interesting; most reviewers are not considering one crucial thing.

The choice is interesting; you can buy into a dead-end platform or pay more upfront for a new one with better-expected longevity.

The 1700 platform is now a dead end (the next-gen will be on a new socket and likely DDR5 only). There are only a few edge cases that can justify buying into it now.

While AM5 is a bit more expensive, it is a brand-new platform where you can reasonably expect 3-4 generations of CPU support. Remember, on AM4, if you had an X370 or B350 board, you could upgrade to a 5800X3D keeping the investment relevant.

Most high-end AM5 boards are expensive because they went overboard with PCIE5 NVME slots even sacrificing usability. Even the midrange ones can support a 7950X VRM-wise. Recent tests indicate that high-speed DDR5 is mostly irrelevant; even latency is getting less and less important as well.