Reserved instance pricing on AWS absolutely destroys Azure. If you do on-demand on both, they look competitive, but there are ways of bringing AWS down which Azure simply cannot match.
Have you had a chance to look at Google's Preemptible VMs? They're a fixed 70-80% off of list price.
Another point is, Google's VMs are generic CPU/RAM combinations. You don't need "network optimized VMs" or "storage optimized VMs" - you simply get those things on any VM. This makes the "excess instance supply" market much more fluid and simplifies folks' lives.
Google's sustained use discounts for standard (non-preemptible) VMs are a huge win as well. No need to predict usage and reserve instance time in advance; the discount is simply applied progressively as you use a particular instance type more during a month.
That's nice, I'm using azure for a windows vm and it's been super frustrating trying to get reasonable performance. (RAM/CPU/etc. is all great but the standard IO is so slow it's basically unusable (i'm maxing out at 10M/s (I think due to iops limitiations).
Another point is, Google's VMs are generic CPU/RAM combinations. You don't need "network optimized VMs" or "storage optimized VMs" - you simply get those things on any VM. This makes the "excess instance supply" market much more fluid and simplifies folks' lives.
Happy to discuss further!
(work at GCP)