Even though I would generally prefer AMD, I read that Intel would be the safer choice.
I guess you’re talking about what you see in the HCL, but do see "AMD appears to lack sufficient testing...and may harbor latent bugs" - Trail of Bits SecureDrop Workstation Review - #18 by tasket this post before judging.
In terms of latest vulnerabilities, AMD has been clearly superior to Intel, and due requiring less mitigations, performance is also better.
Regarding 4.0 and kernel 5.11, if you’re comfortable with building your own ISO, you change the kernel version to the minimum you need, although as you noticed, many people have good experience with Qubes 4.1 (myself included).
If going for newest hardware (which will probably be the best bet) my only recommendation is to carefully choose the Motherboard, specially IOMMU groups (which on some are terrible), I doubt you will have compatibility issues with any modern processor as long they meet Qubes requirements. Also since on Qubes hyperthreading is disabled, having a high core count is desirable (on which AMD offers the best pricing)