The one in my pants
The one in my skull
The abdominals and erector/lumbar spinae muscles. These are the most important, especially when built and strengthened with compound movements as opposed to isolation movements. For example: standing military presses for the abdominals and pulls for abdominals as well as the erector/lumber back muscles.what muscle group is most important to you?... if you could make just one muscle group perfectly built, which one would you choose?
If I had to pick one it is lower back because hurting my back is what going me into lifting seriously and lifting is what fixed it.
The traps, women don't respect a guy unless he has good traps.