I have the 6.5x55mm. I love it for everything. I started with a 264 Win Mag (yeah I was seduced by the dark side) and have always liked the long, heavy for caliber 6.5 140 grain bullets. If I had to do some real heavy lifting with a 6.5x55 I would use a 130 grain TSX Barnes or the 156 grain Norma factory load. Either would do very well. The 7x57 is a great caliber. Both are a great choice. Throw the 260 rem and the 7/08 and we can really confuse ourselves.

Dr Fatguy