I love the Swede, the problem is there are still many surplus rifles out there that limit the pressure to 46000 psi, limiting the potential of the 6.5X55. Also it requires a long action, but personally I don't buy the idea you have to have a short action but many do. If one has a modern action the 6.5X55 will do anything the 260 and 6.5 CM will do.
The 260 is another excellent round but again, too many think they have to use the short action. On this round that requires the longer 6.5 bullet to be seated too deep in the case to fit the magazines. This problem is easily solved by using the long action.
That brings to the 6.5 Creedmoor. The case is designed to allow any 6.5 to be used and still fits the short action magazines. Max pressure of the 6.5 CM is over 15,000 psi more then the 6.5X55.
The CM covers the best of the other two without the limitations.
However, if one wasn't hung up on the short action, and chose a good modern action, the Swede and 260 will work just as well.
I got hooked on the Creedmoor cool-aide because of my wife. I sent her to a Precision Long Range School where she had to shoot their rifles, which was the 6.5 CM, fell in love with it and I had to buy her a RPR in 6.5. Playing with it I decided to try it in a light rifle for deer and antelope so I picked up a Ruger American Predator in 6.5, I too got hooked.
But that doesn't mean I'm giving up my 6.5 Swede Surplus rifle, and I still have the 260 Rem. reamer and HS gages waiting to find a Model 70 Action for my future 260 Rem. build.
I figure, when in doubt, get all three and you're covered.