Haven't read any Pratchett in a while. I have to be in the right mood to read it, but it's good entertainment.
Anything by Janny Wurz is a good bet if you like epic-type stuff. Her "Wars of Light and Shadow" series is amazing. Note to self, must look for the most recent book. Her collaboration with Ray Feist in the Daughter / Servant / Mistress of the Empire trilogy makes them well-worth reading. It's kind of funny, because if you read stuff by both authors (and I like Ray Feist a lot too), you can tell who wrote which passages in the books.
Robert Jordan's "The Wheel of Time" series is one for the long haul, but the later books do lose the quality of the earlier ones. And of course the last book was ghost written by someone else using Robert's notes.
And of course, George RR Martin's "Game of Thrones" series. Which, surprisingly, my mum rather digs. But then she loves historical fiction, and this is in similar style despite being obviously fantasy.
Ann McCaffrey has been mentioned. I like her "Pern" books, but the later ones are nowhere near as good.
I enjoyed Elizabeth Moon's Serrano Legacy (sci-fi), but for some reason, I can't get into her other work no matter how hard I've tried.
And another classic series is David Eddings' Belgariad, which I kind of enjoyed. I have read some of his others from the Malloreon and Tamuli, but I didn't enjoy them nearly as much.
Lastly, the ultimate classic imho - C S Lewis' "The Chronicles of Narnia". Still eminently enjoyable, even if aimed at younger readers.