Terry Pratchet was a prodigious author. You could do a lot worse than then 41 Discworld novels. Whether you begin at the beginning, with The Colour of Magic or pick up from Mort or Equal Rites, or just dive in anywhere because its more a composite of characters dancing around a magical universe than a linear narrative of fiction, you won't be disappointed.
If you want something to seriously chew on, Robert Jordan and Brandon Sanderson are also notoriously prodigious. "The Eye of the World" can be read as a stand alone for a brilliant piece of high fantasy or as the intro to a 13,000 page epic. Meanwhile, Sanderson's "Mistborn" series is a solid, but not exhausting, read with a great opening heist as a hook and a strong payoff at the end of the trilogy.
If you're going for another classic, though, try "Redwall". Brian Jacques is a fantastic writer and his first work is arguably his best (although I've got a special place in my heart for the prequel, Martin the Warrior). Asimov's "I, Robot" is a fantastic anthology of mini-SciFi thrillers. Joe Abecrombie's "Best Served Cold" is a fantastic medieval era revenge thriller. "Redshirts" is a clever little Star Trek inspired comedy that likely inspired the "Lower Decks" franchise. "John Dies At The End" is a comedy-horror that finds a delightful spot right in between J.D. Salinger's Catcher In the Rye and H.P. Lovecraft's The Shadow over Innsmouth.
Don't feel sad your story has ended. Feel glad a new one is just around the corner.
