Having read LOTR many, many times before I ever started trying to read Pratchett, I can't read Pratchett. That's not a slam at Sir Terry; I'd just internalized Tolkien so much that it was beyond my ability to properly appreciate him.
If you haven't tried it, Small Gods is frequently recommended as a standalone, and it's very far in subject matter from the early tolkien-parody rincewind/guards books.
Many Pratchett books aren't riffs on Tolkien at all. Someone recommended Small Gods (excellent choice, and not a whiff of Elves or Dwarves there) but many other Pratchett books are genuinely good and not cheap shots at Tolkien.
I'd say like Bach and Rossini. Rossini was perfectly aware of the form of traditional opera, but deliberately chose to engage with it in a much less reverent style.
