My hunch on why it is considered to be the 2nd in the cloud provider market is due to the most Enterprise size companies already being in bed with Microsoft with a lot of other products and there are a lot of incentives being thrown around to commit to using Azure. Also, there is the "Azure is not Amazon." or "Azure is not Google." Some Enterprise size companies simply won't do business with AWS because they are Amazon. That doesn't meant Azure is a good technical product and this maybe why you are seeing GCP vs AWS more often in technical comparisons.
For example, Azure was a consideration for our "not AWS" cloud provider until we tried to use custom Linux images with at rest encryption on the root volume. It's simply not supported and there was no viable work around. There was also no ETA for adding in support for this non-negotiable customer requirement. This is why we moved onto evaluating GCP. So far it has been pretty great and it is checking a lot of our requirements that Azure either fell short with or flat out didn't support.
For example, Azure was a consideration for our "not AWS" cloud provider until we tried to use custom Linux images with at rest encryption on the root volume. It's simply not supported and there was no viable work around. There was also no ETA for adding in support for this non-negotiable customer requirement. This is why we moved onto evaluating GCP. So far it has been pretty great and it is checking a lot of our requirements that Azure either fell short with or flat out didn't support.