Both cartridges are good, solid cartridges. The Creedmoor is a little easier on the shooter, and bucks the wind better. 308 is more widely available, by a large margin. 308 is also far easier to spot at long range. Darkker and I were shooting both at 1680 a summer ago, and the 308 was relatively easy to spot, whereas the Creeds were _very_ tough. Plus, there's a mighty fine 308 barrel, already threaded and with a highly effective brake on it, in the classifieds right now...
Lothar-Walther SS 308
:)