PANF+ does have finer grain than FP4, but I find it hard to control the contrast with PANF+ - too many blown highlights and not very subtle midtones. I find FP4 much easier to work with and more forgiving. I have souped the 2 films in either ID-11 or Microphen.
I have seen PANF+ developed in Rodinal which seemed to give a better dynamic range but increased grain.
FP4 has quite finer grain compared to Tri-X so that would be my recommendation.