One look at America should tell you that "Free Market Capitalism" does NOT slow down corruption of government. In fact, unless it's strictly regulated, it actually encourages the corruption.
I don't really know what the best system would be, but it would have to have to incorporate parts of socialism and parts of free market capitalism. In my mind, certain things should be state run, such as mass transportation, utilities, and hospitals. All else could and probably should be privately run. Some regulation would have to be in place of private industry to limit environmental damage, poor workplace practices, guarantee wage levels and so on.
I would say something in the direction of what Germany currently has looks fairly good.