There might be more people using the creedmoor if lapua made brass for it. I shoot with a bunch of tactical/precision shooters, some capable of winning national matches, and more shoot the .260 than the Creedmoor. That being said I don't think the majority of them are using Lapua brass. You can get more powder in a .260 case and some push them a bit faster which certainly helps a bit shooting to 1K or farther. At a recent match they had targets out to 1400 and a friend shooting a .260 cleaned it. :) I don't think you can go wrong with either one.

I've got more than five loads on the Hornady brass and I've only tossed a few for loose primer pockets after a couple thousand rounds. If you don't reload the creedmoor has a big advantage with cheaper factory ammo. Winchester recently started making ammo too. If you're going to be swapping barrels I'd look at one of the 6mm rounds too for 3-600. You can get the LRP in .243 win as well.