Great question! Back when watercolor was first introduced, I did several. As a result, I have a LOT of floral fabric, but I got tired of making them. Before and after that fad, I like to try new things, and if you look through my album of quilt pictures, you'll see that they are all different (except for the watercolor period). I love to try new ideas, and I usually tweak them a bit to make them 'mine' in some way.
My favorite quilt SIZE is lap - big enough to show the fun of a pattern, but not so big that you get bored. I can no longer hand quilt, and machine quilting this size quilt isn't a wrestling match.
Every once in a while, I get the urge to paper piece in order to get SHARP points. When I finish that quilt, I say 'never again.' Of course, the memory fades, and a year or 2 later, I paper piece again. If you haven't paper-pieced, the reason: PP is time-consuming, even though it produces perfect blocks. And you have all that paper to pick out when you finish . . .