Azure and AWS just posted their strongest cloud numbers in years, yet the companies that stand to benefit most from this surge are neither Microsoft nor Amazon.

Microsoft ( NASDAQ:MSFT | MSFT Price Prediction ) and Amazon ( NASDAQ:AMZN ) reported earnings back to back, and cloud was the biggest story for both. Azure grew 48%. AWS grew 39%, its fastest pace in nearly five years. Both companies say demand still exceeds supply. That is good news for every rival that rents out computing power.

Azure Speeds Up While AWS Props Up a Soft Retail Quarter

Microsoft beat on both earnings and revenue. Non-GAAP EPS came in at $4.89 against $4.72 expected, its sixth beat in a row. Azure revenue reached $33.17 billion, and growth accelerated from 43% last quarter. Amy Hood, the CFO, credited the engineering teams: “Those efficiencies… they’re sort of ground out every week.” PCs are the weak spot.…