I like both!

Okay I would definitely say Harry Potter or Star Wars.  Considering that I haven't seen either Lord of the Rings or Star Trek, I cannot make an adequate comparison between either of the pairs.  I've never had any interest in seeing either of these other movies.

Harry Potter unites us all through its account of an epic, common human struggle.  We can all relate to its timeless plot.  It takes an ordinary boy and makes him into an extraordinary protagonist.  He is "the boy who lived."  He represents the ability to overcome any obstacle that might be in one's way.  His courage and determination triumph over evil.  He represents the purest form of "good," and his story is one of the classic good vs. evil.  

Star Wars fuels the imaginations of so many young people, and allows them to reach for something more.  When you think of action-packed space adventure, what pops up first in your mind?  Star Wars, without a doubt.  Both Harry Potter and Star Wars are simply classics that many Americans hold near and dear to their hearts because of their entertainment value, the lessons we learn from them, and because of their relatable, independent characters.