I'm going through a mitered border phase, though I used to do straight borders for a long time. I'm just saving the long pieces from the sandwiches I have to do (using 108" backing) and make my future quilts according to the size I get from them. I've got a couple quilts on my to-do list that will only take binding to finish, no need to put borders on them. I think it's just easier now to do mitered corners, it takes a bit more fabric to do them, but everything just looks incredible with them than the straight borders. Pieced borders would definitely give everything a scrappy look, though.