Iono, I read a lot of them.
The City Watch & Death,respectively, varieties are the best of the series. Feet of Clay and Reaper Man easily rank above all the other novels.

My favourite is Mort or The Reaper

i love books with reaper or with vetinari or withches

and the humor is great i read almost all of his books ( 30+ i read maybe he got some more i didnt )

and T.P. might seem as books for childern but i know some ppl who are 40+ and really enjoy it

actually all terry pratchett books are kinda heavy on philosophy/sociology/politics/astrophysics/... kids could read these books, but they wouldn't get even 10% of all the hidden jokes/puns/wisecracks

it's really hard to have favourites, but i think i like the books with Sam Vimes the best (Guards!Guards!, Feet of Clay, Thud!). although there isn't one books of T.P. i dislike...

Guards! Guards!

and as hatemonkey i just loved lugage in Ricewind books. I hope there will never make a movie based on this couse its just imposibble to show everything like it is in book.

The Dark Side of the Sun is another great book if you wanted to read that.

Only read around ten, actually reading Small Gods now.

Any book with Sam Vimes is great, love that character. But Going Postal and Night Watch are my favourites so far.