Just look at the username.
As for best books...um...all of them?
Alright, I can pick a few at least. Guards! Guards!(the first one I read), Interesting Times, Reaper Man(anything with Death, in fact...so all of them again), Mort, Eric, Men at Arms, and the Wee Free Men books(Hat Full of Sky was great!). Hmm...Mosntrous Regiment and Nightwatch are great too. Bah! I can't pick.
Shilsen's really nailed it with Pratchett's writing on the human condition. The characters are just so great. And they've inspired not just one D&D characters. Had a Druid with a very Rincewind like attitude towards nature itself. "I like nature!...as long as it stays outside."