I'm a total magpul person. over the years i bought or have been given brand X and different metal mags and they always end up never being used for one reason or another. You used to be able to get online deals for buying 5-10 at a time.
My prefernce is 10 shot because of weight and the 20 & 30's stick down too far for lots of rests.
APF for a while made their own designated design mags for 22-250 and 243, but don't see them anymore. For now, I just use any for 308win/7.62x51nato mags.