I like the .308 in military guns and with 146, 150 to 168 grain bullets.As a rule a .308 winchester round is more accurate than the .30-06.
The .308 vs the .30-06 look pretty close with 150 grain bullets,but the 06 starts kickin ass with 165-200 grain spitzers.The .308 does not have enough case capacity to push these bigger slugs to velocitys that the 06 can.
with 150 grain slugs and 22 inch barrel the .308 push's about 2,800 fps,the 06 generally push's that same slug 2,950 fps,150 fps does not sound like much but when you one step up in bullet weight it drops 200 fps less than the 06 so on and so forth its a viscous cycle.
I dont own a .300 win mag,but for my 18th birthday my dad bought me a Weatherby Mark 5 Deluxe in .300 Weatherby and it has a brake on it,and I love the gun but its not a Plinker even with a break its a beast.But with any magnum round bullet selection is vital unless you plan on taking your shots over 300 yrd or more,ballistic tips and plain jane soft points tend to just blow up on game at close range particulary on Boar or heavier game.
Premium grade bullets like Nosler Partition,Trophy Bonded,Swift,Winchester Fail Safe,and others do a really good job in magnum calibers.
Trophy Bonded Bear Claws seem to do good in all calibers.I use Federal Premium 180 grain TBBC and they are Viscous on game.My cousin broke both shoulders on a 340 pound feral hog with my rifle and this load and the damage was herendous.The distance was about 85 yards.