I have been shooting 260 Remington since the late 90s. I've owned at least three different Savages chambered in 260.

That said, I recently switched to 6.5 Creedmoor (still have my 700 Mountain LSS in 260, though). The reason for me was simple - factory ammunition, which means time savings with my current life situation.

Ballistically, they're pretty much the same although the 6.5 Creed has a slightly shorter OAL which is friendlier for AICS mags if you plan to run those and VLDs (Hornady 140 A-Max/HPBT, 139 Scenar, 142 SMK worked just fine in an AI mag with the typical .118 freebore found in Savage 260 prefits), so flip a coin.