I have used .270, 30-30 and 25-06. My first deer was taken with a .270 in the Ruger M-77 at 280 yards with a fixed 4 power Weaver.
The 25-06 is a Ruger M-77 also. Today, I would still use the .270 if mule deer hunting. My youngest son took his first deer with a Marlin 336 30-30 at 180 yards.