LSUfan71 has the right idea, and, for under 100 yards, the old 30-30 is tough to beat. There just isn't any significant ballistic difference in the three calibers mentioned. But for use anywhere in the US, at any reasonable hunting range for everything up to the big bears, the 30-06 is unbeatable! The .30 caliber provides a big difference in wound channel diameter thus the ability to find the shot deer! In the immortal words of P. O. Ackley, the greatest American gunsmith and cartridge tester in US history, when ballistics are similar, the advantage will always go to the larger diameter bullet. The 30-06 is easier to find on the shelf in most stores than any other round. The 308 was developed for semi-autos - short actions are nice but how much does 1/2 inch shorter bolt mean if you give up even a little performance. Secondly, there has been a run on 308 ammo due to the semi-autos folks have. Furthermore, 30-06 has more bullet options than any other cartridge. Finally, the 30-06 (especially when handloaded) and the 7mag are almost identical ballistically, but most 7mags run 1 to 1-1/2 pounds heavier in most sporter rifles. Why carry the extra weight and barrel length for similar performance? Many have tried and advertised but none have truly bettered the old 30-06!!!