The correct answer depends upon which survival situation - they aren't standardized. Survival is a bit like cave exploration. Some passages favor big people and quite often there are constricted passages suitable only for a tiny person.

The correct answer is probably "both of the above" - a well coordinated group which intelligently uses the capabilities of its members.

I have heard that for maximum survival when resources are scarce, the honed, six pack ab types will not fare as well as those who, while still reasonably athletic, are just a tad overweight (belly fat = emergency rations)

Take the boy your parents gave you and do what you can to improve its capabilities....

What does being a bigger target have to do with it? Are you just focusing on civic strife situations and violence?