Wow, up until now I only associated Gartner with the magic quadrant, had no idea they had this.
It doesn't seem like they'll give you up to the hour information and you do have to pay for "Gartner for Professionals" which I'm not familiar with but it's definitely out there.
The key to this has to be supporting it cross cloud IMO -- people have the AWS vs GCP vs Azure conversation so often and I think most people know that GCP is best performance for the buck, but the other reasons to pick the other two are numerous. Might be nice to have some numbers on just how much performance differs against the others since that's one of more quantifiable things to weigh.
Not sure if the data is freely available, but I used to be part of the team at AWS that calculated these. See [0].
[0] https://www.gartner.com/en/cloud-decisions/benchmark-library