The 30 BR, 308 win, 30-338, 300 win, 300 wsm, 308 baer, and 300 ultra all have great accuracy potential and they will be very consistent with load tailoring for daily conditions. All the above have seen lots of action on the 1k benchrest circuits (except for the 30 br which is kicking but at 300 yd hunter class right now) and are proven winners.
However, none of the above cartridges can compete at 100 or 200 yards on a daily basis with the 6ppc. Not even the famed 6br which I love (I have two) can beat the 6ppc on a daily aggregate. It has won a few relays and even a few matches, but across the long haul the ppc will ultimately win out.