Amazon still holds most of this market, and its competitors are looking for any way possible to infiltrate the market, as such, there are many opportunities for companies, especially startups to leverage this momentum for their side.
Having said that, we are working with Microsoft Azure, for several reasons.
The current state of the Azure cloud is in between stages, main infrastructure change, this leads to bad documentation and sometimes to bad user experience, although the functionality is there and sometimes extremely easy to use.
There are two ways to use the Azure, one is the classic model and the other is the resource manager.
The classic model has all the documentation and explanation a developer of a sysadmin could ever want.
The resource manger is mature in its abilities but still lack some of the documentation and easy to find how to articles.
The recommended option by Microsoft is the resource manager.
An example for this use case is how to create a virtual machine, with Linux OS, modify it and then save it as a custom image.