Microsoft Azure

Strengths: "Azure is already a very capable and broad platform, and Microsoft continues to accelerate its new-feature velocity," said Gartner. The innovative capabilities being launched are no longer just copying competitors, according to the research firm.

Customers committed to Microsoft technologies are frequently choosing Azure as a strategic cloud provider.

And in a "vital and positive strategic shift," Microsoft has become been embracing open-source technologies.

Cautions: While Microsoft is a highly experienced enterprise software vendor, some clients told Gartner the Azure service "feels less enterprise-ready than they expected."

Those customers cited issues with technical support, documentation, training and breadth of the ISV partner ecosystem -- issues Microsoft is addressing.

Gartner assigned some fault to Microsoft's channel.

"The disorganized and inexperienced ecosystem of managed and professional service partners" has made it difficult for some customers to find experts, fostering reluctance to deploy production applications or migrate entire data centers, according to the research firm.