I was doing a placement year for the third year of my university degree (Politics & International Relations), and I thought that it'd be a great time to try actually living in another country instead of moving through quite quickly, and also sneak a few months traveling in before having to come back and completing my degree.
I hadn't been to South America before, but I'd heard a lot of great things about Argentina from a few friends that had travelled around South America. I picked VG out of the organizations I looked at partly because I got a nice friendly vibe when I e-mailed some questions, but also because it is a smaller independent organization, and I felt I'd be able to have more of an impact there as opposed to come of the huge volunteering "corporations" that I encountered online. It was also partly financially, it made no difference in terms of the donation I made to the organisation that I was staying for a long period of time (all placements over 3 months have the same donation), whereas many others I looked at charged the same month on month no matter how long the placement was.