Cash-on-Cash Return is what you would use to compare your investment to other types of investments, like stocks. To calculate Cash-on-Cash Return, take the Annual Cash flow and divide it by the Down Payment amount.
Annual Cash Flow
Lets see it with an example from Camden Towns.
Investment Anaylisis from HarrisonburgInvestmentProperties.com
This is a continuation of a serious entitled: The Top 10 Terms of Commercial/Investment Real Estate.