Given the capabilities of both rounds, I would lean towards the 300 WSM
for the following reason: Better choice of bullets with higher BC's. The 325 WSM case holds three more grains than the 300 WSM. For me, that is not enough of a difference to offset the selection of bullets. Compare similar weight bullets for each caliber. You just can't get the BC's in the 325 that you can with the 300. If LR shooting is the goal, my nod goes to the 300 WSM.