_Why Azure vs Competitors
Microsoft is a trusted supplier of technologies used to build applications that run businesses. Windows Azure allows applications to be built on top of a highly available platform that takes care of failover, redundancy, fault tolerance and backups. The pay-per-use model, in conjunction with the architectural approaches taken when developing for Windows Azure, allows applications to be built that are highly scalable. Applications can respond quickly to shifting user demands without the need for an expensive, idle infrastructure. The base building blocks of Windows Azure applications are commodity (virtual) machines. Costs are directly measurable against consumption and investment can be spent on development, versus expensive equipment and licences. The application stack of Windows Azure is recognisable with ASP.NET, WCF, SQL Server and other technologies - this allows existing investment in people, approaches, frameworks and other assets to be directly transferable to Windows Azure.
Other providers
We maintain that Windows Azure is the best platform for our clients and the applications they build. We are always happy to give you our professional assessment of other cloud platforms and products.
Amazon Web Services
While innovating and introducing products at an astounding rate, Amazon Web Services suffer from two problems. Firstly, because EC2, as the base building block, is self-administered a lot of effort is needed by devops specialists to configure an automated cloud environment. Secondly, Microsoft .NET is not a first class application stack on Amazon Web Services and there is, for example, no database service for SQL Server.
Google App Engine
Once seen to have the potential to change the way applications would be built, it has since suffered from a lack of direction. Only recently did they settle on an instance based model (accompanied by disruptive pricing changes) and the introduction of a SQL data service. Google App Engine has a lot of catching up to do.
OpenStack
Aggressively supported by Rackspace but, as an attempt to form an open cloud standard, suffers from lethargy and arguments between various stakeholders that does not exist with proprietary cloud stacks. CloudFoundry (sponsored by VMWare) suffers from similar afflictions, as well as being new and untested. All open cloud stacks still require further decisions as to the right place to host the application, making them, at least for now, little different from traditional hosting.
Force.com
Primarily a Software as a Service (SaaS) provider. The rigidity of the platform, combined with a proprietary and niche programming language, makes it unsuitable for the building of business specific applications. Heroku, owned by Force.com and hosted on Amazon Web Services, is a cloud platform that caters more to the hacker community of Ruby, Python and Node.js than it does to application stacks familiar to the enterprise.