Warning: highly opinionated post follows. Friendly disagreement more than welcome.
It’s been a couple of years since an entirely gratuitous Terry Pratchett thread, and a Twitter discussion asked about favourite Pratchett novels, with a focus on readers new to Pratchett. What think you?
My overall favourite is Night Watch, but I think it would be a terrible place to start reading: you need the context of the earlier Night Watch sub-series for background. Night Watch follows Guards! Guards!, Men At Arms, Feet of Clay, Jingo and The Fifth Elephant. You could possibly skip Feet of Clay and Jingo and have most of the background, but that’s still a fair commitment. You want The Fifth Elephant because it introduces the major characters in an ongoing multinational inter-species political struggle (Monstrous Regiment, Thud!, Unseen Academicals, Snuff), but it’s also probably not strictly necessary as background to Night Watch.
The Night Watch sub-series is also interesting technically, as Pratchett has created two absurdly powerful political characters in this series (Vimes, the head of police, and Vetinari, the ruler of Ankh-Morpork), and has to come up with increasingly aggressive scenarios to actually challenge them. He has written elsewhere about finding this annoying when he wants to write interesting stories in Ankh-Morpork without Vimes sticking his nose into them.
It’s worth warning that Night Watch is one of the darker novels, with offscreen torture and onscreen immediate-aftermath-of-torture. Small Gods has similar warnings (religiously inspired torture), if you’re OK with that it is good and very self-contained, and has also served as an entry point for a number of people.
The first Discworld I ever read was Hogfather and I think it’s actually not a bad starting point, since it’s a fairly self-contained story and contains a bunch of core Discworld themes concerning how magic and divinity work. It also has a great heroine who unfortunately, in my opinion, otherwise appears in pretty mediocre Discworld novels.
Probably for most Hoyden readers I’d recommend starting with Equal Rites or Wyrd Sisters and reading through the Witches novels, which is where I went after Hogfather. The Tiffany Aching books didn’t exist at the time, but they’re very much in the spirit of the Witches novels, except that the Witches seem much more organised in them: Pratchett can’t leave well enough alone when it comes to creating power structures. See tigtog’s post about the Witches for more.
I find the Rincewind/wizards sub-series pretty unworthwhile, and still haven’t actually read all of it, so I can’t speak to that fairly.
Edited to add: there is a well-known reading order guide, which lays out the various sub-series in a flowchart style, but I cannot find an accessible version. Hence this post refers directly to the sub-series wiki pages.