alt Hacker NewsI suppose the value of this depends on your threat model.
The TPM will give you stronger assurance that a machine owns a key, but it's likely that a dedicated HSM would be much harder to extract the key material from.
TPM being inside the machine is a double edged sword. On one hand it makes attestation feasible, but on the other you now have the security black box inside the same physical domain as the machine that uses it. Risk of side channel extraction goes up dramatically when these systems coexist. It's a lot harder to instrument an HSM across the network.
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A dedicated HSM will give you stronger trust that the private key material can't be extracted, but there's no real way to bind an HSM to a specific client and that's a very easy thing to do in the vTPM case.
TPM is just a spec, it isn't necessarily a black box.
ARM TrustZone, for example, can run this OSS TPM: https://github.com/OP-TEE/optee_ftpm
I expect there are equivalents for Intel/AMD.