I voted .25-06. I think my .25-06 shooting 117 Grain boat tailed Hornady custom ammo is probably deadly for deer out to 400 yards, which is further than I ought to be shooting anyway. I also have a .243 which I will use instead of my .25-06 which I'm also pretty confident is deadly out to 300 yards, which is probably about the limit for where I should be shooting big game animals. I'm not a trophy hunter, just a mature doe or buck for good eating and a good hunting experience, hence there isn't the need to reach out to the absolute max when the ancient stag of the forest taunts me with his monster rack from across the canyon. I also have a .30-06, and I have used it for deer before -- but it is substantially more than I need. I would be happy using any of these guns I mentioned, but I feel the .25-06 is probably the best match of "enough but not too much" gun for the deer.