The first finishing badge you should get in 2K21 should definitely be slithery and contact finisher. That is because these badges give you great leverage over your opponents. For example, a slithery finisher allows you to avoid any injuries caused by bumps or attacks. It allows you to slip past your opponent smoothly. And the contact finisher gives you great and consistent contact with your layups. This means both these badges will allow you to goal and win more easily.