I get both, but I rarely seem to end up using more than one or two pre-published modules a year.
My current game, however, is entirely based around putting together two mega-modules - Return to the Temple of Elemental Evil and the Banewarrnes. I figure I'll throw in as many prepublished adventures in the between spaces as I think I can get away with.
I prefer writing my own games, but time is an issue for me at the moment. I'd rather spend the free moments building the world rather than the individual adventures.