I noticed that different books have a different sign convention for LFSE.  The new editions of Miessler, Shriver and Housecroft uses the negative energy convention (- delta o + paring energy), while the older edition of Shriver and Huheey uses the positive energy convention (+ delta o - pairing energy).  

I'm curious, how do you teach LFSE? the negative or positive convention?

Which one is a better approach to the LFSE?  Do you know of a literature reference for this?