Here you will Find Effective Concept which helps you to choose cloud Server which i have used practically and got success. so please find it below.
1. Cost: Whenever you go for Cloud Server, first check packages from all vendors with detail technical specification which they are providing. also compare with others and also include implementation cost in vendor price.
2. Ability : It is the most Important thing. Check that you can afford server parts and other maintanance of your application or not ? if you cannot then don't go for cloud server.
3. Security: Check the Vendors Reputation in Market and also learn Security risk of the cloud server.
4. Also check that you want all control or not ? if you want all control then choose personal cloud.