I recommend everything Pratchett has written.

Hogfather is a great book, but it's also one of four dozen books that take place in Discworld. While all of his books are enjoyable on their own you will find if you read more, the author has very carefully interwoven them together. https://upload.wikimedia.org/wikipedia/commons/7/73/Discworld_Reading_Order_Guide_3.0.jpg

This is a great time of year to read the HogFather, if his approach to beliefs interests you, consider reading Pyramids or Small Gods next.

If you really like Shakespeare, check out his "witches" series, which features Granny Weatherwax, easily one of my favorite characters in all of literature.

if you like the cities and police procedurals check out "Guards Guards". If you're interested in the industrial revolution sub-series, I would still recommend you read "guards guards" first, as it helps set the stage for a lot of the Ankh-Morpork based books.

If you like fantasy, "the color of magic" is rough, being the first book he published, but it is classic. It was the first diskworld book I picked up, and I remember laughing out loud within the first few pages. It also introduces many staple characters, like Death.

Speaking of Death, if you enjoy the hog Father, you might consider Mort, and the rest of the Death subseries. I don't think any author but Pratchett could humanize the anthropomorphic representation of a concept like death so successfully (except perhaps Neil Gaiman).