NEW YORK ( TheStreet) -- My kids love to play rock, paper, scissors. You know how it works: Rock beats scissors, and paper beats rock, and scissors beats paper. There are no tie-breakers, and there is always a winner.That same principle applies to REIT investing. There are the primary asset sectors of housing, office, retail and industrial. All of these sectors provide needed space for their occupants, and some are considered better than the others at different moments. As we all saw, during the great recession, necessity-driven sectors were in highest demand. Core survival-based categories of food, shelter and clothing became more relevant for investors, as their fixation on sustainable income and dividends became critically important. Conversely, successful investors learned that the strongest sources of differentiation are found in those companies with the most sustainable business models, built on repeatable sources of income.