I shoot hundreds of 308 & 3006 bullets, reloads & store bought. I take your message to refer to the store bought ammo.
While all the MAJOR Ammo Mfgs have excellent ammo on the market, My first place vote would have to go to Federal Premium.
Federal offers a great slection of premium bullets in these calibers and their loads are very consistant - even from lot to lot.
My favorite 308 is their P308C which uses a 165gr Sierra Gameking bullet. Out of my Remington rifle I get sub-MOA. For 30-06 I find that the P3006D (same bullet as above) is also very accurate & the P3006F using a 180gr Nosler Partition is excellent for hunting as well as accurate in it's own right.
Hope this helps, k