Easiest way I've killed Tigers and King Tigers is simply flank, if someones near you have them take pop shots to get his attention, with a 34/85, Panther and M18 simply run to get a clear good shot from the side, make use of terrain and be patient.
Most tankers are not, thus why they get killed moving around to much.
Panther is a medium tank, its apples to oranges trying to compare, just use the panthers strengths to tigers weakness, 3 shots is more then enough to kill a Tiger/ before its turret swings around.