I've read a lot of them & if I had the space would collect them. Recently I was seriously looking at the Art of Diskworld, but decided to just wait till I see it in the library (or maybe on sale, but where will I put it?)
I loved Maurice & the Time Monks & Sam & DEATH & the Patrician is an interesting character, too.
The Last Continent had me laughing continually, as did Maurice & his talking rats.
The most recent books I read were 'The Science of Diskworld'. I found Vol 2 in one of my local libraries, so looked for Vol 1 & found it in my other library, then read them in order. Strangely enough, one library classifed them as fiction, the other as non-fiction. I did like the Elves, but I was very pleased when the Wizards won!!
Unfortunately the both libraries seem to have run out of un-read Diskworld books. Tho I suppose I could borrow one I've already read.