I am that weirdo that LIKES to work on one at a time. If I get too many going, it freaks me out.
I pick my priorities by deadlines or by alternating techniques. For example, right now I am in the midst of a HUGE curved piecing pp'd project which mean my next one will probably be machine applique, OBW, then a log cabin, then a Thangles by the time I get through those I will be ready to do pp'ing again.