Academically, your gain would be about the same if you choose whichever direction. But MBA could provide you with a hugh alumni network which you can make use of for the rest of your life. Also, the management courses/experience during your years as an MBA will not impose an impasse if you could like to climb a management career ladder. If you want to be a specialist in finance, MSF will be better in that you will be more focused on the area. In a nutshell, it depends on you career goal.