6.5 Grendel for me in every way. A 16" grendel pushing the nosler LRAB has reliable expansion out to 700 yards, and is supersonic nearly to 1k ay sea level. I own a 6.8, and like it, but the Grendel can do everything a little better, and has become WAY more popular in the last year alone.
Fedral now has 4 loads for the grendel, a gold.medal match line, and even a 90gr TNT load pushing 2900 fps that comes in a box of 50!