The " best" one would be a rifle that you are comfortable with and can shoot accurately. As far as cartriges go there is really no " best" . Any of the normal " DEER" cartriges (243, 260, 25-06, 270, 280, 7mm-08, 308, 30-06, 257 rob., 7x57, 6.5x55, 7mm mag, 300 mag, the list goes on and on) are more than capable of taking any whitetail that walks this earth and the majority of those listed I would feel very comfortable hunting elk and moose.

The 270WSM I would list as an excelent whitetail cartrige and a very capable elk and moose cartrige.