How Do You Choose the Right Criteria for Employee of the Month in a Large Team?

I am working in a container terminal as an HR Associate, and I've been chosen to lead an Employee of the Month project for 750 employees distributed among different departments: operations, finance, HR, facilities, IT, and security. I need to determine the best criteria for selecting an employee each month and the basis for making the selection.

Normally, the best employee is given to the one who is close to the manager or the one who is always behind the boss... definitely not for hard workers in today's corporate world.

What sort of a reply is this?

We ought to be passing on sensible and meaningful information to each other.