RE: .243or.260or.280
As far as accuracy is concerned, the .260 Rem kind of gets the best of both worlds. Let me explain...6.5mm bullets are very long and stable, and are considered by accracy nuts to be some of the most accurate around. Also, the .308 Win case, on which the .260 is based, is also known for producing outstanding accuracy.
I've been around several .260s (most of these custom rigs built when it was still called the 6.5mm/.308 wildcat), and can tell you they are scary accurate.
One other thing to consider: My buddies who own these things do not hesitate to load 140gr premium bullets and whack elk and moose at pretty respectable ranges. None of them has ever lost an elk they shot with their .260.
Good Dogwork and Good Hunting