I’ve tried both Intel and AMD, I personally like AMD more because of the symmetric cores. That said, Intel wasn’t a worse user experience in terms of running Qubes OS.
It’s mostly the motherboard you need to worry about, until someone has confirmed Qubes OS is working there is no way to know for sure. I don’t think there are any guidelines, you can use the HCL to get and idea about what vendors has worked with prior chipsets.
If you want to know for sure it’s going to work, buy hardware that is confirmed to be working.