Server Decision Between CPU VS RAM

[Xon]

The server will run 1 Xenforo forum 100-200 concurrent users, 3 Opencart stores (total 800-1000 visits everyday),

The hardware you are specing out is vast overkill.

IMO 4v CPU 4gb of ram VM from Linode should be able to handle that sort of load for a combined website + database.

I would prefer the Intel myself which is per core, per clock a better cpu, the fact that a web server threads out well enough the extra cores might balance the difference in practice. If your ram usage is going to be high I think the AMD setup would actually be a good move.

XenForo is fairly sensitive to single threaded performance for a number of things.

I notice it most when installing addons for Digital Ocean (NY1) vs Linode. (Linode is on average MUCH faster).

KVM does absolutely nothing. It's still a shared server with shared resources. You are at the mercy of other clients. If another user crashes the server, your VPS goes down, XEN, KVM, OpenVZ, whatever. Shared is shared.

SSDs in shared hosting forgive a multitude of sins.