Public Cloud Partners
Microsoft's Azure cloud hosting platform provides a cost effective way to quickly spin up servers. Using the pay as you go model, Azure allows a faster time to market combined with reduced costs over owning a server.
Azure's design is oriented towards hybrid cloud, where your primary infrastructure is still on-premise.
Azure Active Directory (AD) integration often makes it the right choice for extending a domain joined server to the public cloud, as it allows for single sign on.
Amazon Web Services
Amazon's Web Services (AWS) has similar pricing to Azure and offers similar features. Not as focused on hybrid cloud, Amazon AWS servers are a viable choice if you don't need AD integration. AWS offers a unique private space for government agencies that have made it the go-to public cloud service for government agencies.