#2 RackSpace

This company is the leader in cloud based web hosting and encompasses managed services and pure hosting businesses.  Gartner analyst Lydia Leong says that Rackspace is presently in the second position when measured interms of revenue and Virtual Machines. The company’s public cloud service revenue rose to $189 million in fiscal year 2011, up from $100M the previous year according to gigaom.com

Comparing Amazon’s EC2 and Rackspace: If one intends to scale on EC2, they need to launch additional instances (which you can do with stored AMI’s). At RSC, you just have to point to a running instance and click a button to say “Make this server bigger” (or smaller if you need to scale down). A few minutes later, it’s all done. There is an option of adding additional instances, too!

#3 Google

Google is one of the major player in internet technology and with its Google App Engine platform as a service the company has made it to the list of top cloud service providers. Google is one amongst the few companies that has the potential to invest in core computing firepower to give a tuff competition to Amazon web Services. Google’s cloud service is aimed at developing and hosting web applications using Google’s infrastructure and data centers and additional advantage is that the engine supports several languages including Java, Ruby and Python. The main selling point of the company is their scalable service that allows developers to pay for what they use without startup costs or recurring fees.