This is just IMHO of course.
Some folks really hate the 308 Winchester round, even though its been a proven performer on every big game animal in North America and in many other parts of the world.
The 6.5 Creedmore is the new "in fashion" cartridge that won't really do anything the 308 Winchester will do other than sometimes be more difficult to find in out of the way places when you're on a hunting trip and you've forgotten the box with your ammo in it at home.
If you don't handload, then my suggestion to you would be the 308 Winchester as every commercial manufacturer in the world produces it and depending on where you shop, there is a wide variety of bullet weithts, shapes, toughness available, with either special order or off the shelf.
That being said, there are no flies on the 6.5 Creedmore and with good premium hunting bullets it will do every bit as good a job as the 308Win and usually with a slightly better trajectory out to longer ranges over 300yds.
Price wise, for the rifles and the ammunition, there isn't much difference, until you start getting into custom builders or high end producers.
Both cartridges are inherently accurate IMHO, as long as the rifle is capable of good accuracy and is fed ammo that suits it.
Interesting that you brought this up. Last thursday I was at our local range with four different rifles. Two were mine and I was checking them out to make sure nothing had gone awry over the winter, as Bear season starts here on Apr 1. The other two belonged to long time friends that had just purchased them and wanted scopes mounted. The Model 70 Winchester was brand new, as were the Burris scope and mounts and it was chambered for the 308 Win. The other rifle was a Savage Axis that was picked up used but looked new and already had bases and rings but needed the new Athlon scope mounted and sighted in.
Both of the owners of the rifles aren't handloaders and in their mid seventies. They aren't about to start now.
Neither of them are cheap when it comes to purchasing good quality "premium" factory ammo, with proven hunting quality bullets priced at 69.95/20 round box. They each gave me two boxes for the sighting in session.
I cleaned the bores on each of them, back to the steel, with Wipe Out and took them out to shoot.
I set up 25 yard targets and 100 yard targets. Then bore sighted them to get the scopes which had been set to their turret's mid points as close as I can see and set the zero rings.
To my surprise, the very first shots (two each) were within 3/8 inch of each other at point of impact from both rifles. I just love it when that happens.
I cleaned the bores again and shot them at 100 yards. (three rounds each) and happily the groups were again surprisingly tight, under 1 1/4 inches.
For factory rifles, shooting commercial ammunition, that's very good IMHO. It's also unexpected for the most part.
I adjusted the turrets until I felt they were set to shoot these factory loads two inches high at 100 yds. Both were close enough when two more shots were fired from each rifle.
I cleaned the bores again and gave them back to their owners.
When you get an off the shelf, factory rifle that shoots really well from a freshly cleaned bore, that's a rare thing. Two rifles from different manufacturers at the same time doing it is like winning the lottery.
I am amazed at how good off the shelf factory built rifle barrels are these days. They don't foul as quickly as they did ten years ago, which were better than their predecessors as well.
I expected the 6.5 Creedmore to foul more than it did, simply because the velocities were faster. Didn't happen.
Today, both of those gentlemen came over to pick up their rifles and chat. I asked them to take the rifles to the range themselves and shoot them, but let me know the results.
They're both good shots and know how to properly utilize their front and rear rests. I'm hoping there won't be any changes.
The fellow with the new Model 70 can be a bit lethargic for my tastes when it comes to cleaning the bores on his rifles. I have the last one that he said he could no longer get to shoot well with the ammo he preferred to use. Well, the only thing wrong with it was a badly fouled bore.
Sometimes, when bores get that badly fouled, it's next to impossible to bring them back to fine shooting accuracy. Luckily this one isn't bad and it's one of the Remington 700 BDLs with fancy grade wood from the old Remington Custom Shop. I might even persuade myself to keep it.
OP, what I'm getting at with this long winded diatribe is that both of the cartridges you mention are kissing cousins perfomance wise, if you do your homework and maintain them properly.
Then of course, there is the "scope'' you intend to mount. I've seen a lot of good shooting rifles get maligned because their owners put on cheap scopes that are loaded with parallax and no way to adjust it out or the internals barely stand up to the recoil generated by the cartridges they're shooting.
I would also suggest you look very closely at a decent scope and mounts to go with whichever rifle you acquire. A good scope, is a must IMHO. Hitting what you're pointing at if far more important than the cartridge, as long as it's capable of the job at hand.