I think if you took a random 10 factory 300WM rifles and a (similar) 10 random factory 300 PRC rifles, used ammo of the same price range, the PRC are going to on average shoot better. It's a better designed chamber.
If "good enough" is ok for you then sure just get the WM
I'm not sure why online ammo availability is even part of this discussion?? I want boxes on the shelves. I've been in 1 Scheels, 2 Cabelas, and 2 Sportsman's Warehouses in the last few weeks, waaaaaay more PRC on the shelf than WM. It was the same way through the last ammo shortages too.
I'm betting the majority of you in this thread also could buy a 300 PRC, 5 boxes of ammo, and be set for the next 10 years .