I like the .243 because it is a short action cartridge, easy to find ammo for, ammo is a little cheaper and it does a great job on any deer that you'd shoot!

The 25-06 is a good cartridge too! My dislikes of it are: long action and it is really beyond the "varmint class."

As for the .260, I"ve never shot it. It is a short action cartridge and "on paper" it looks to be an ideal whitetail cartridge! As with the 25-06, the .260 isalso beyond the "varmint class." From what I can tell, the .260 has not caught on well with the shooters, so it is going to be hard to find ammo forunless you reload. Sadly, it looks like the .260 will go the way of the 6MM Rem. and the .257 Roberts! Good cartriges, that are dying from lack of popularity.
One good thing about the .260 is that if you do reload, you will always have a supply of brass from the .243, 7MM-08and .308if it does become commercially extinct!

My choice is the .243 because it is truly a dual purpose cartridge, that serves both sides well!