I'm sure someone can expand more, but according to most of the latest articles I've seen: Neither, although both have benefits, with Citrulline providing the most benefits for performance.
IMO, I notice the most vacularity/pump from PWO's that contain carbs and BCAA's, and some with L-Norvaline and/or Agmatine. But Carbs/BCAA's seem to be the common theme from my own experience.