My own stuff, all the way. I'm not really big on reading several source books for each campain, its mostly a time issue, I guess. I don't like getting the 'facts' of a particular setting wrong, even if the DM has the final word, if I use a published setting, I prefer to stay adhered to the rules. Its much easier to make things up as you go, when the world is entirely your creation.
Sometimes I use maps. Not too often though.
Not that I haven't had fun playing modules. Some of our best role-playing was done in a series of three Ravenloft high-level modules. But as far as plot line, and how everything ties into the world, I find it easier to create the story if I can create the whole world.
-Mike