Amazon EC2 was the most reliable compute and Google Cloud Storage was the most reliable storage.

The Laguna Beach, California company tracks status of more than 30 clouds from AWS to Zettagrid:

Service provider Outrages Downtime
Amazon EC2  20  2.41 Hours
Amazon S3  23  2.69 Hours
Google Compute Engine  72  4.41 Hours
Google Cloud Storage 8  14.23 Minutes
Microsoft Azure Virtual machines  92  40 Hours
Microsoft Azure Object Storage  141  10.97 Hours

Read More: https://gigaom.com/2015/01/07/amazon-web-services-tops-list-of-most-reliable-public-clouds/