the kind of ROI that degrees used to give earlier is not available these days. The market is very bad ever since the financial down-turn.
Just to help you decide better I shall share the following link:
Skip the MBA: 3 Reasons Why You Should Get Real-World Experience Instead | LinkedIn
I would suggest you that if you wish to pursue higher studies, do so, not from the point of view of ROI but from the view of what you want to do.
There is a famous quote -
"I do not know the key to success, but the key to fail is to try and please everybody"
Put down your strengths and weaknesses, and do a study on the MBA as well as MA curriculum and then as per your interest choose wisely.
Also note that there would be difference in profile with the two degrees.
While MBA can give you options to work into any role of HR - recruitment, employee enagagement, training, performance, etc;
MA would give you more options that involves psychometric.
A BA(Psycho + Socio) and MBA has its own advantage if you can club psycometrics to HR functions.
Hope it helped