This is a hard question. The answer is that it really depends on your application. There are many cloud computing providers out there. The industry leaders are:
What solution does Fly My Cloud use?
Most of our platform requirements are fulfilled by Google Cloud and Amazon AWS. We deploy most of our client applications using our middleware (which performs the autoscaling) on Google and Amazon platforms as well. However, depending on the requirement we do sometimes recommend going with other providers such as Microsoft Azure. A typical use case will be a user who also need Azure active directory along with other services.