Picking a CMS is a daunting, but necessary, task. The platform that powers a website will influence how it is built, maintained, updated, and more. It is a significant investment in time to learn a new CMS and an investment to maintain. I just read an article that very clearly lists the factors to consider in this decision at Web Designer Depot. I cannot say which single CMS is best for every situation. I doubt anybody could, but this article is a great start for finding what is best for your project.