This study evaluates and selects an optimal portfolio using the fuzzy prioritization method and COPRAS based on criteria derived from investors' preferences. The first sample consists of 30 water-intensive companies listed on the Tehran Stock Exchange, and the second sample includes 17 academic and professional experts. To determine the criteria for selecting the optimal portfolio based on investors' preferences, the first phase involved identifying criteria through a review of literature and previous studies. In the second phase, Delphi sessions were held with professional and academic experts, and the output of these sessions, along with the literature review, resulted in the identification of over seven key criteria, including stock return deviation, stock liquidity, price-to-earnings ratio, profitability, return on equity, research and development expenditures, and company image (reputation). For weighting the criteria, the fuzzy analytic hierarchy process method was used, and a pairwise comparison questionnaire was given to 17 experts to assess the relative importance of each criterion. Based on the results obtained using Excel 2016, the criterion “Return on Equity” was ranked first among the criteria for selecting the optimal portfolio based on investors' preferences. Based on the final ranking of the options according to the weighted final indices, Pegah Khorasan, Shiraz Petrochemical, and Nush Mazandaran companies ranked first, second, and third, respectively.