Lapua is best, but they haven't made any for about 4 years. If you find some Lapua up for sale, you might wanna jump on it. RWS is pretty good also. Tough as Lapua, but a little less case capacity. Periodically some RWS brass will show up for sale.
I'm not sure if Norma .300 Win Mag Brass is tough or not. I'm sure it would be dimensionally uniform. Just don't know how tough the case head would be and how high of pressures it'll take before the primer pockets loosen.
I started a Thread years ago attempting to learn more about Norma .300 Win Mag brass, but never got much feedback.