LotR was the first fantasy book I've read (in my country fantasy books we very rare and obscure, and being young I couldn't import fantasy books, nor did I know they existed
).
There are many excelent fantasy books nowadays... But none of them inspired a sense of awe, enchantment, and suspension of disbelief, like Tolkien's works did.
It's a black & white book, I liked that (although I also love grittier books with many shades of gray... But that doesn't have to be a rule!).
I loved the pace. I value many other aspects above action scenes and such. FOr me, two hobbit adventuring for the first time to the outter limits of the shire was a great adventure for me. The sense of something wonderful about to happen has always been more appealing to me, then the marvel itself. I love the beggining of the journeys more than their climaxes.
And then, a full realized world, with races, cultures, languages, myths...
For me, Tolkien will always be the master. Maybe because I'll never be that young and naif again.