Sierra, Berger, and Lapua, in no particular order. See what your barrel likes. In 6.5 and 7mm there are also Jlk's that work very well. Probably more customs out there that are known in their locale.
In 6mm, there are various offerings from custom makers. Randy Robinett makes a heavy 6mm.
Usually the customs will shoot as well or better but most barrels have a preference that you have to find.
Come down to Huntsville and shoot the Texas 600 in a couple of weeks.
Joe