If I picked one single shot pistol from whitetail through elk class animals, it would be my 7mm Dakota XP. With 160-190 grain bullets I can deal with any game animal I want, at about any distance I want.
If shorter and mid-ranges were in mind...6.5-284 or 284 Winchester XP

If I was picking one revolver for deer class animals it would be my 357 Magnum Franken-Ruger


Ernie the Un-Tactical