Among the many things I love about the Discworld novels are the descriptions of people. Terry Pratchett often manages with a few sentences to paint a picture that is often a bit funny, sometimes slightly weird but always hits the nail right on the head.
As an example, these descriptions of the witches in Lords and Ladies:
"The first one - let us call her the leader - flies sitting bolt upright, in defiance of air resistance, and seems to be winning. She has features that would generally be described as striking, or even handsome, but she couldn't be called beautiful, at least by anyone who didn't want their nose to grow by three feet."
"The second is dumpy and bandy-legged with a face like an apple that's been left for too long and an expression of near-terminal good nature. She is playing a banjo and, until a better word comes to mind, singing. It is a song about a hedgehog."
"The third, and definitely the last, broomstick rider is also the youngest. Unlike the other two, who dress like ravens, she wears bright, cheerful clothes which don't suit her now and probably didn't even suit her ten years ago. She travels with an air of vague good-natured hopefulness. There are flowers in her hair but they're wilting slightly, just like her."
I also found this one in my collection of quotes, but I can't find out where it is from. Does anyone know? I think it might be my favourite.
"Many people could say things in a cutting way, Nanny knew. But Granny Weatherwax could listen in a cutting way. She could make something sound stupid just by hearing it."
Do you have more examples?
I just read them in release order over and over again, takes me about a year each time. You get a good feel for the whole Discworld universe, and it makes me reread the few books I think I don't like (because I usually do like them, but remember some aspect poorly)
Having said that, I would order the series: Guards > Witches (Weatherwax) > Von Lipwig > DEATH > Tiffany Aching