Pretty much preference. They will all do fine on deer with the right bullet. With the wrong bullet you will curse out all 3. Bullet selection is best in .243 and worst in 6.5. But still plenty of good choices. If it will also be used for varmint, the 243 shines.
Yep, and Im leaning towards .243 for a number of reasons..
1) Im comfortable shooting elk sized critters on down with a .243
2) I already have all the "stuff"
and
3) Im cheap and looking for a new take off Remington barrel in .260 isn't panning out...yet...
