Personally, I choose the freedom of action😆 but let's see what the cynologists are saying.
The main advantages of a collar and a leash are practicality and total control over your pet, including management in training when practicing commands. On the other hand, a harness is attached not to the neck but the dog's upper body, and the load is evenly distributed on the back. If your dog pulls you forward, the harness won't squeeze its throat or make it hard to breathe.
Harnesses are traditionally available for smaller dogs, but large, strong dog breeds usually need a stricter approach, especially in training, so a dog collar is a good choice. But it is not forbidden to use a harness either👌
A collar for training is much better than a harness because it makes the dog feel your power and authority. And the harness will be a good choice for everyday walks. Therefore, it is convenient to have both in your inventory.
What ammunition do you use for walks with your pet?