To choose the right server for your needs decide on the following.
What type of applications will you be running, and how many?
What type of processors do you need, and how many?
What type of switch ports do you need to support the server, and how many?
How much memory do you need?
How much power do you really need?
For a good VPS server I recommend VPSdime.com as I've been using them for hosting a blog for 4 years now without any issues.