FWIW, my three favorite oils are PP, PU, and Amsoil XL. After trying oils such as RP, M1, GC, Rotella T5, and a few others, I feel that PP, PU, and XL have given me the best results. This is of course purely subjective - no UOAs, but my engine has been smoother and quieter when running these.
PU and XL are both excellent oils. My advice - if you really want to know which is 'better', try a couple OCIs with XL and then a couple with PU. Either you'll find you like one better than the other, or you'll find they both give you equally good results.
Personally, I don't like to get caught up in the Grp. III/III+/IV/V arguments about 'synthetic' oils. The 'best' oil for you is the one that yields the best results in your f150, not the one that looks the best on paper.