Goal: how do you walk a dog?

Which of the following methods is more reasonable for accomplishing this goal?

OPTIONS:
- attach a leash to the dog's collar, and then let it walk in front of you outside, but hold on to the leash to maintain the power.
- let it run free outside.
attach a leash to the dog's collar, and then let it walk in front of you outside, but hold on to the leash to maintain the power.