I am getting a new rifle, make/spec TBC but a very important part of the purchase is the calibre.
My areas of comparison would be ammo availability, cost, barrel life and lethality/energy retention.
If barrel life is critical, then forget 6.5PRC and 284-6.5. You will get about twice the barrel life from a 284W, but you will have to reload. Good for 1000 yards and plenty of bullets to choose from.