Being practical-minded, choose a cartridge with readily available Brass, dies, and reamers.
No downside to a std 280 with 160s at 2930 with IMR 7828 and Fed 210s.
280 AI is the easy button, formed brass can be hard to find, try forming your own out of Lapua 30/06 brass where you do not lose primer pockets at top-end accuracy nodes.
Another easy button is the std 6.5/06, and I am shooting the 129's at 3150 with R#26 into very, very tiny groups, CCI 250s. 127g Barnes long range was very easy to tune, .050 off the lands, 129g Nosler long range accubond, and 129g Hornady SP(a bullet that never lets you down). All the bullets in this weight shot so well with R#22, I never worked up a load with the 140-ish bullets.
The 6.5/06 seems to be an idiot-proof case to work with when tuning a load. I am running Win and PMC '06 formed cases in the 6.5/06.
270 Win brass would be a better choice to form brass with in regards to the 280AI and 6.5/06 AI, but you use what you have on hand. The formed neck is a tad shorter than the chamber, and the use of the Teslong bore scope allows you to see the carbon build up in the neck and easily remove it with a few twists of a bronze bristle brush of the appropriate size.
6/284 Lapua brass is a thing of the past, as of right now...Europe is preparing for war with Russia.
Russia is about to kick the war into another gear, more of our own reloading supplies will disappear, aka PRC brass....maybe.
Concerning Match kings, I lost a really good buck a few years ago during the rut. He stuck his head out on a power line, the range was 320 yards, chip shot for my 7 Mag's MV of 3150, 150g MK. Buck was knocked down, I saw the blood on his shoulder blade through the 6-24 scope. He got on his feet, and was never to be found after two days of looking.