6.5 PRC, hands down. .264 Win Mag is inefficient and wasteful.
I did not expect this comment so early in the thread, but I almost completely agree:
Get a 270 Winchester, 3 times the barrel life as the 264 Winchester mag and twice as easy to shoot precisely.
In this class of cartridge,
I own a 6.5-284 Norma, and a .270 Win.
My brother owns a 6.5 PRC, and a .270 Win.
As far as we are concerned, they're all .270s.
Very similar velocities. Very similar bullet weights.
They're all long actions.
I wanted to play with a 6.5-284 Norma for a long time. But I couldn't convince myself that it would be fun, due to the extreme lack of variety of 6.5mm bullets on the market (and, 10+ years ago, rarity of .284 Win brass, let alone 6.5-284 brass).
The impetus for changing my mind, however, I owe to .260 Remington and 6.5 Creedmoor. The rise in popularity of those two cartridges, the 6.5 Creed especially, caused an explosion of new bullets to hit the market.
My 6.5-284 Norma moved from questionable and limited, to viable and worthwhile.
But the only thing that sets it apart from .270 Win is the slightly better ballistic coefficient of the bullets.
I was out a few weeks ago, testing 143 gr ELD-Xs in the 6.5-284. The velocity was only 30 fps slower than what my go-to 140 gr load clocks in .270 Win.
Then again...
The rise of 6.5 Creedmoor paralleled the increasing interest in 'long range' shooting, which has given us high-BC bullets for nearly every other caliber.
There are now readily available .277" bullets just as sleek and slick as the 6.5mm stuff that we drooled over 10 years ago.
They're all .270s.
As for the PRC, specifically:
It seems to be decent. My brother has one that's doing quite well - not as well as his Bergara .308, or my kludged 6.5-284, but it's still new to him and hasn't had loads properly tuned yet. It shows promise.
But, again, it's just a .270 by another name. ...With expensive and usually difficult to find brass and ammunition.
New things are fun to play with. If that's a motivator, go for it. Nothing else needs to be said if it's just a matter of, "I want one."
If it's just the general class of cartridge that's being considered, a boring old .270 Win is the most economical option. ...With ammunition and components available
everywhere - and usually at lower prices.