What in your opinion would hold more value to a potential employer? a post graduate with less work experience or a graduate with more work experience

A post graduate may have less experience, but the maturity and depth of knowledge and understanding one possesses outclass the number of experience.
Eventually the experience will build up with post-graduate as well, but there would be a vast difference between the two.

depends on when you would rather to spend money, now or over a while and depends on whether or not you already have enough resources that can cover the required tasks until the new graduates are ready

It all depends on what the employer is looking for.
Sometimes it is better for an employer to have less experienced employee so they can teach them the way they want things to work not an experienced person that is going to do stuff the way he or she knows.

A graduate with more experience always better than post graduate. 

 

A Graduate with more experience