RE: 25-06 270 30-06
30-06 all the way.
More types of ammo available. The ammo is less expensive. You can get 30-06 ammo anywhere.
270 is a close second.
25-06 deserves honorable mention, but the other two cartridges are better cartridges. However the factory ammo for 25-06is way too expensive. Operating cost of a rifle for the rest of your life is important. If you want to practice with your rifle then the 30-06 will cost less money, it is that simple.
You will hear a few guys tell you that dead is dead, and that the 25-06 will kill deer dead. And it will, no doubt. However we have shot a lot of deer with all 3 of the above cartridges, and if planting the deer in their tracks is important to you, then the 30-06 is king of the 3 you mentioned.
Some hunters will complain about the recoil of a 30-06. And it will recoil a bit more. However unless you have a physical problem then the 30-06 recoil is easily manageable. And if you are recoil shy then I would go with a lighter cartridge than what you listed. There is not a lot of difference between those 3.
The bottom line is the difference between these cartridges is cost of operation. Why would you pay more?? Tom.