I'm going to have to go with the 30/06 on this one. The 06 is more available than the 308. There are more factory loadings. It is legendary in its widespread use and ability to do whatever people seem to ask of it. With a single shot there really isn't any benefit of a shorter cartridge. I have seen a lot of very accurate 06 rifles too. A side note is that I have always disliked the 308 because when I was growing up the only guy who had one that I knew was a real prick. The bad feelings kind of stuck on the 308.