Sure you can!
True, if you were entering a raffle, any of the above should work very well for you...
BUT, you're not buying "never been fired" rifles. How old are they, and which one of the three did grandpa use the most, and why?
How old are the scopes?
Did grandpa wear out the barrel on one, and put up his "old friend" on an "honored" spot on the wall, and switched to a different rifle? Maybe one of them doesn't shoot so well any longer and simply needs a good copper removal and cleaning of the bore?
The cartridges' ballistics overlap by a huge amount. Did grandpa reload for each, or only some, or did he find factory ammo that worked well in each? Did he "buy" all three, or did he win one or two in a raffle, and put them on the rack, and kept shooting his favorite? Maybe he started with the .270, and switched to the .25-06 to reduce recoil as he got older..., and the 6.5 Swede was a raffle prize? Maybe one or two were bought as the price was amazing, or he was helping out a friend, or perhaps one or more were gifts?
A lot of what if's..., but I don't think any of them from what you wrote, are "bad" choices.
The .25-06 Remington you don't hear about much these days.., but it's been around for more than a century, it's older than the .270 Winchester AND the manufacturers are still offering it in rifles. There must be something to it...
LD