#1 - Discworld Series by Terry Pratchett
The Colour of Magic. This 'comedy' seemed to be the latest thing in fantasy so I bought it, read it, chuckled at the jokes (especially when the camera imp ran out of pink paint) and then bought The Light Fantastic, the next in the series, to read the rest of this two part story. I also lent the books to a couple of my friends who also enjoyed it, which helped to build my interest in these books.
However, to be honest, the first two Discworld novels are probably the worst of the series. Since then they have steadily improved and the recent novels are far different beasts to those earlier works. Now the books skip along, telling exciting stories but still with Pratchett's wit and thinly-veiled comments on modern society.
It has become something of a ritual where, every Christmas, I will gratefully receive a new Terry Pratchett novel from my in-laws. I think I have all his Discworld books and love them all to bits. They are the books that I do not hesitate to buy - or request as a present - and the books I'm most likely to reread. As such, they are probably my favourite series of books (at least at the moment!).