Lankaneau and Einstein seem to be the easier places. Christiana is supposedly easiest of all and pays well. Abington is easy too and I've heard is rather lucrative for prelim year because of a signing bonus. Pennsy Hosp is not bad either.
Cooper and Jefferson are probably two of the worst for prelims because of work-hours and number of call months.
I understand Drexel is ok, but not as easy as the community hospitals. Unfortunately Graduate is no longer.
I don't know much about prelim at Temple or HUP, but I assume that they are bad for prelim just based on their volume and location. I'm not sure if Presby has a prelim program, I assume not.