Leader: Amazon Web Services

AWS has been at the top of the IaaS heap for more than a decade, still the most popular choice among enterprises looking for strategic, organizationwide cloud adoption.

The Amazon division closed out last year with a run rate exceeding $14 billion.

"It continues to be the thought leader and the reference point for all competitors, with an accelerating pace of innovation on top of an already rich portfolio of services, and an expanding impact across a range of IT markets," Gartner noted.

"AWS has just begun to adapt to the emergence of meaningful competitors," said Gartner.

There's little you can't do in the AWS cloud, although complex legacy applications with strict compliance restrictions need special attention to architecture.

"Transformation efforts are best undertaken in conjunction with an SI," the research firm noted.