Well the classic answer we read all the time is 'the one you shoot the most accurately'. There is a lot of truth in that sentence but as many of us here know, it is not always that simple. As stated before all those calibres are capable with correct projectile choice, shot placement and in most environments. I went with the various 7mm's. I don't like a lot of recoil so I shoot a 7x57 very well. I've also had a lot of success with a .308W on plains game and less satisfying success with a 9.3x62 because of poor (non expanding) SN projectile choice. I'll never take advice again without testing on something first. If you are a trophy hunter and just have to take the first shot presentation given to you then yes, the .375H&H is the best choice. If you are in open country like the grassveldt then the 300 magnums will work a little better. Give me my 7x57 with a conventional 154 or 175 projectile. I'll need a bit of time to pick my shots but if the range is long or close it will work for me.