The Harry Potter books are easy to read and fun, because they are kids books, and there is nothing wrong with that.
The LotR books are difficult to read, complex and immersive.
I prefer LotR because they require more mental thought and effort to read and understand, for that very reason I find them more satisfying and immersive. I also can’t see Harry Potter being considered a classic in 100 years time, if its even remembered at all. I can see Tolkiens work being remembered for a long long time.
I also think comparing the literary quality of the two is a complete joke.