With same length barrels, the .260 will slightly outperform the 6.5x47, but the difference is marginal, and in ballistics almost neglegable. Lapua brass available for both, cost of components very similar. With longer bullets in a Remington factory rifle the 260 will have OAL issues, but if you have a long savage magazine or plan on doing a wyatts internal box or AICS, then the 260 would be a little better imo. But, the 6.5x47 has a better shoulder which will aid in less trimming. However....
You could go .260 ai and have a MUCH better performing cartridge than either....if you reload and don't mind forming brass, which isn't a big deal.
My .260 ai is shooting 140 berger's at 3140 with rl26, and I can get 3025 with H4831SC. That's topped out. My go to load with the berger 140 and H4831sc is 2930, and I just worked up loads with rl26, and from 3040 fps all the way up to 3140 fps groups were in the .2's to .4's and my SD was single digits and es was 13 fps or less, the lowest was 7. This was only 3 shot groups, but it still looked very promising to shoot 5 different charges and have the largest group fall in the .4's....Needless to say I'm biased towards the .260 ai.