The easiest way is to determine which codec is best for you, is to consider how much bandwidth is available in your business scenario, and balance that with what quality you are comfortable with.
While both G.711 and G.729 are very good quality. There is a difference (however slight it might be audibly). As a rule of thumb, G.729 is slightly less then the quality of an excellent cell phone call while G.711 is typically better or at least equal to the quality of an analog land-line.