I used to advocate the harness for small dogs rather than a regular collar.
I still do.
I've now seen the advantage with larger dogs too.
With a tiny dog, a collar is like a noose. As the dog pulls, pressure is placed on the delicate trachea.
When the dog pulls back, the collar tends to shift and you could possibly end up with NO dog on the end of the leash.
The same thing happens with big dogs.
The harness gives the owner a lot more control and spreads the pressure throughout the body of the dog.
I've witnessed embedded collars and permanent indents in a dog's neck from the daily wear of a collar.
Please consider using a decorative collar along with a harness for pictures and events.
Your dog may not be able to thank you but will be safe and comfortable.