Most effective rifle for hunting??
Every rifle I have in my gun safe is most effective for what it was designed for.
Most are great for hunting deer, some effective for varmints - 2 or 4 legged ones.
Animal to hunt, distances to cover, distances to carry said rifle during hunt, all are an integral part in determining what is the "most effective" rifle for an individual. For me who hunts white tail deer on "only" 15 acres of land, I cannot determine what is "most effective" for someone who hunts moose/elk having 300-450 yards to shoot over and carry the rifle several miles during the hunt.
I probably did not answer your question, but the question is too broad to really provide any single answer.