People say whoever wrote the plays must have been in the courts of Europe. I say that person was never there. Shakespeare's portrayals of court scenese were the result of great writing, great imagination, some reading, and whatever he may have actually seen in England's court. His portrayals were hardly documentary, nor were they meant to be.
I think the Earl of Oxford was proposed by a few, too. And Bacon. I once read a book called Bacon is Shakespeare. I found that convincing, too.
The best argument against Shakespeare the actor being Shakespeare the author is that actors then were like actors now: low-lifes, ignorant, etc. I like theories like the ones mentioned because they make me more interested in the history of the time.