Talk to your tax advisor if you want to pay down one early to see where the greatest benefit for you would be. As for return I don't know about you but on your investment in the current envionment you would control the property for about 25,000 out of pocket. Principle and interest would make a payment of 698.00 a month. If you can not make a return of 10% a year on your 25000.00 you need to look at your rental rate or your purchase stratagy. Appreciation and paying down the mortgage on the investment are just the icing on the cake.