36-Way Comparison Of Amazon EC2 / Google Compute Engine / Microsoft Azure Cloud Instances vs. Intel/AMD CPUs
Obviously it's important to match the workload to what you would be deploying in the cloud, but hopefully you will find at least some of these reference benchmark results useful.
Obviously keep in mind too there are many other instance types available on Amazon EC2, Google Compute Engine, and Microsoft Azure, while this was just testing a subset of those.