5. IBM

2016 revenue: $77.8 billion

2015 revenue: $79.6 billion

IBM's channel has been transforming in recent years with the "cognitive transformation" of the 105-year-old technology giant. That includes providing channel partners with the opportunity to resell its solution to extend on-premise VMware installations to the IBM cloud. (IBM struck the partnership with the virtualization leader last year.) IBM has also introduced new competencies around security, cloud-based video services, its Watson Internet of Things platform and offering IBM financing to customers.

Big Blue's channel will also move forward under a new channel chief: Marc Dupaquier, announced recently he's leaving at the end of June, and will be replaced by IBM veteran John Teltsch.