Forbes recently cited a Gartner study that put Amazon at the top of the list when looking at computing power...by far. Money quote:
"Amazon Web Services remains the king of cloud, according to Gartner’s latest research: In fact, the amount of computing power it is supplying customers is more than ten times that of the other top 14 cloud providers combined."
This was a topic discussed recently at my office. It's a little difficult to say, because there isn't a standard measurement to use, and when it comes to revenue, the companies don't all measure it the same way. As best I can tell:
1. Amazon (AWS).
There was an article earlier this year on ZDnet that broke it down, but there was some speculation in the numbers. This was especially true for Google. After all, how are they breaking the revenue figures down? It's not really clear. As ZDnet said, "Unfortunately, it's difficult to declare a winner since every cloud player has its own math. So much for standards kids."