What are you going to do with your new rifle?
If its just general stalking and medium game shooting within 200m, it doesn't really matter which one you choose from a performance point of view.
What separates them is their medium to long range capabilities. If you want to really get the best out of the 6.5 calibre, you want to use the longest, heaviest bullets, and that means you need the chamber and magazine dimensions to allow the extended COAL. That's where the Creedmoor has been such a success.
You may read a lot of gumpf about the .260 Rem being limited in that it won't fit the longer 140gr+ projectiles into the magazine, or give you the flexibility to maximise COAL. Whereas the Creedmoor will do both of these. That is generally true of many of the original .260 Remington rifles. However...
My main shooting buddy bought a 20" Tikka CTR in .260 Rem a few weeks ago "for his wife". He took his COAL gauge to the shop and a bunch of ready made .260 cases with ELD-X pressed in at a range of seating depths. Clever man! He didn't want to not be able to use the long, high BC bullets with the Tikka which of course only his wife will use, ever. So now he is loading Hornady 143gr ELD-X to 2.900" COAL and they chamber and fit in the mag easily and cycle fine. The rifle is matching our 24" 6.5 Creedmoors with the same bullet pretty much yard for yard, you can't separate them.
So at least in the CTR, it looks like Tikka has addressed the COAL restriction of several earlier rifle makers. It certainly is a lovely rifle to handle, a very good option for our kind of shooting where you might find deer at 50m, or 500m. Only woosies will say its too heavy.
I went with a heavy 6.5 Creedmoor for prone shooting of long shot strings because I wanted to shoot the goats I couldn't reach with my .243 Win. And it is that accurate, that easy to shoot, that my tallies have gone through the roof since the beginning of the year. It's a bloody marvel with the 143gr ELD-X and its turned a fair few heads down our way, me and my buddy both have them in Howas. When we set up looking across a wide gully to a large opposing face, say 1100-1200m long left to right and 600m max range, there's very few goats that make it out alive. Considerably more productive and pleasant to shoot that the .30 cals or 7mm Rem Mags we've used in the past.
So yeah, depends what you want to do. You wouldn't be disappointed with the Tikka CTR, but you'd want to reload for it to get the best out of it.