What he said! I've run 243, 6mm Rem, and 6 Creed, and the Creed is my favorite, hands down. If the 6 Rem was designed correctly (that is the rifles made to shoot the 6 Rem), the 6 Rem could mop the floor with the 6 Creed. But even given proper twist and freebore, the 6 Creed would still be a better round because it's easier to tune as stated above, and it's easier to tune in large part because of the quality brass available. Everyone makes small and large primer brass- Alpha, ADG, Norma, Lapua, Peterson, Starline, and Hornady and Nosler at least make LRP cases. Even PPU and Winchester have offerings (I think) in LRP.
Next, you can always find brass because no one makes rifles chambered in it for the masses anymore. When I say that, I mean there are no sub-$1000 rifles unless there may be a Ruger American Predator or something like that. Browning was making them in all their X-Bolts, but as far as I know, they' only doing that in a high end Pro model now, I think. I bought one in a Savage Desert Tactical the first year they introduced the new modular tupperware with 26" Savage Vamint weight barrel. I did run a tuner brake on it, but I very quickly and easily dialed in way-sub-1/2 MOA groups with 103gr ELD-Xs and Reloader 17 with speeds over 3100 fps without pushing it. 7.5 twist. Savage might still have one, but I'm not sure.
The reason you can readily find brass is because no major maker has them anymore. It's people like us on this forum that keep the demand for the brass up. It was the only round I know of that never completely went out of stock everywhere. Only mainstream round, anyway.
It's like the 7mm SAUM. They had a gem on yheir hands when they introduced it, but only us long range hunters and competitive shooters saw the advantages - many of which has been made obsolete by the Sherman line, but still...
I think my all-time favorite 6mm is the .240 Wby. That's an apples and oranges comparison, and this isn't the place to debate it, but it's not one you plink with or you'll be replacing a barrel soon. I will definitely own more 6 Creeds!