I'm really not a fan of Star Wars and less so of Harry Potter, but I can't believe Potter is winning. I suppose as we all age the world continues to change. That being said, while Harry Potter seems like a cash-in can anyone really deny that Star Wars wasn't and isn't any less so. Star Wars invented merchandising.
Also, I haven't read the whole thread, but comparing Harry Potter to LOTR (although probably a more apt comparison) is a very hard comparison to make. LOTR was an initial publishing flop, but it became a very important work in our history. Embraced by the hippie movement and influencing rock bands including Led Zeppelin, not to mention it's influence with video game design, it is a far more important work than Harry Potter can ever aspire to become. However, what's better is not always the most important and while I'd like to champion LOTR, I honestly couldn't make it through the series.
So... to each their own.
(I voted Star Wars)