Orchard is the MVC cms of note.
If you are going to pick a pre-built CMS, pick it based on the merits of the CMS. MVC vs Web Forms probably doesn't matter too much here if you know what you are looking to build.
If you are intent in building this yourself and you are comfortable with Html, Css and Javascript then you probably want to do MVC3. Presuming you have some underlying web skills, MVC3 really has erased most of the potential productivity advantages of web forms.
