LotR just has a much more epic story. that and i really enjoy Tolkien's writing style over Rowlings anyways. Tolkien was always much more detailed, and that's what i love when i read.
the other big plus is that the LotR movies where just better all around than the HP movies (thus far). and regardless of how well done the next HP movies are, its going to take a monster effort to top Return of the King. there is no other movie out there that tops it in terms of how epic it is.
See the struggle of the faithless lot as they negate their time
How low to sink to the depths of their frame of mind