Hi,
Each of those templates will allow you to create a web application in Windows Azure using different flavors:
- ASP.NET Web Role: This is the classic ASP.NET
- ASP.NET MVC2 Web Role: This is ASP.NET MVC using ASP.NET views
- ASP.NET MVC3 Web Role: This is ASP.NET MVC with support for Razor views
Now if you have to make a choice, I would go for ASP.NET MVC3 (and soon even ASP.NET MVC4) web roles, because these are the most recent versions of the "web platform" with the most features.
Sandrino
Sandrino Di Mattia | Twitter: http://twitter.com/sandrinodm | Azure Blog: http://fabriccontroller.net/blog | Blog: http://sandrinodimattia.net/blog