Asking for advice on RAM.

DDR5. It is overall better than DDR4.

I would not go for Intel at the first case.... AMD is way better, mainly if speaking about passively cooled PC. Putting aside that Intel takes much more energy and is manufactured on node with much lower density (10 nm vs 5 nm) the big-little is the main problem. You may end up to be forced to disable all 'efficiency' cores. So, why to pay for them?

DDR5 is better/faster. 64 GB is pretty much for most users. Unless you plan to dive heavily into classical/cinematic music. Few years ago I had 8 GB. It became limiting, so I expanded to 16 GB. It was so, so. So, when I have built new PC a year ago, I put 64 GB inside. But I use little over 16 GB and few GB from this is used by graphic card....

And I expect that your PC will have four memory slots. Would be desirable to use only two slots for now, so that you may expand if more RAM needed one day. You could add 64 GB more and maybe even 128 GB more one day....