The .25-06 is a perfect deer gun. Its a little much for varmint shooting, prairie dogs and ground hogs, all day shooting might be alittle rough.
The .243 is also a good deer gun, I shot a doe at about 140 yards with it this year. It was my cousins rifle, I was holding it as she crossed a fence and a doe ran out at the bottom of the field, one shot and the folded up and rolled about fifteen yards. If I were using a .243 I probably wouldnt want to go over 200 yards or so, and It would have to be a good angle.
The .260 I have no experience with. Ive hunted with a .264 win. mag. but I dont even know if those are close to the same thing?
-Jake