Gee, this was a toughie!
I have read all the Harry Potter books and
loved them all (yes, I was one of those dorks at the bookstore at midnight on it's release date

) But, the HP books were written for a younger audience so some of the writing and plot lines were a little 'simple', for me (not slighting JKR in any way here, swear

) .
LOTR is, of course, epic and always a great read. But it never really grabbed or fascinated me like it did for
so many others over the years.
I am in the process of reading through
The Wheel of Time series by Robert Jordan, at the moment, and oh my! I adore it. The intricate plot with a multitude of characters, groups, clans, nations and alliances. Every character simply comes to life and the development and maturation is wholly believable and understandable. I'm currently on book 8 of the cycle so I decided not to go with an 'other' vote, but highly recommend it to any 'high-fantasy' saga fans

So what the heck did I vote? The Dark Tower, of course. I've read many King books but, had not really drawn many connections between them until I began DT. The scope and 'name-drops' from other King books, the 'meta' feel that the series has (an over-arching reality that many of his books work within), the fun of going back and re-reading other DT related books with DT in mind, and reading some of the other connected books that I had never really had much interest in until starting DT (ie; The Eyes of the Dragon). I'm just starting the last book in the series now and am torn between rushing through it to see was goes down and wanting to slowly savor the deliciousness.