Leader: Microsoft Azure

Microsoft Azure maintains a firm second place in market share for IaaS and integrated IaaS and PaaS. But while Microsoft currently appears the only true challenger to Amazon Web Services, Azure still lags behind the industry leader on both axes of the Magic Quadrant -- only slightly in Completeness of Vision, more so in Ability to Execute.

Microsoft's cloud, originally born as a PaaS offering, offers a rich set of capabilities, including a container service, CDN, batch-computing and serverless computing, Gartner noted.

After years of high growth, Gartner estimates Azure achieved a run rate at the end of last year of about $3 billion.