RE: New deer rifle.....
There's a guy who comes up to my camp every year with a .300 WM, and a .30-06. Uses both--depending on his mood, and whether or not he's walking through the woods on a drive, or sitting on a stand.
Personally, I'd use a .300 WM on something a bit larger than a whitetail, but, to each their own.
BTW--welcome to the board!