TheStreet.com Ratings provides exclusive stock, ETF and mutual fund recommendations using proprietary tools. Our "safety first" approach aims to reduce risk while achieving total return performance.BOSTON ( TheStreet) -- The following companies have market values of $50 million to $500 million and receive "buy" ratings from our proprietary quantitative model, which considers more than 60 factors. They're ordered by their potential to appreciate, starting with the company with the best growth prospects. American Physicians Service Group ( AMPH) provides medical professional liability insurance and investment management services. The numbers: Second-quarter net income decreased 20% to $4.9 million and earnings per share fell 17% to 70 cents as revenue declined 13% to $20 million. The operating margin dropped from 51% to 38% and the net margin decreased from 35% to 24%. The company has an ideal financial position, with $46 million of cash, compared with $6.5 million of debt. A debt-to-equity ratio of 0.1 confirms fiscal prudence. The stock: American Physicians Service Group is up 4% in 2009, underperforming major U.S. indices. The stock trades at a cheap price-to-earnings ratio of 8, but doesn't pay dividends. Balchem ( BCPC) sells specialty performance ingredients for food, animal feed and pharmaceuticals. The numbers: Second-quarter revenue declined 16% to $53 million, but net income surged 45% to $6.9 million and earnings per share climbed 44% to 36 cents. The operating margin improved from 12% to 19% and the net margin advanced from 8% to 13%. Balchem has boosted cash reserves 926% to $27 million since the year-earlier period. A quick ratio of 1.9 indicates a strong liquidity position, and just $6.8 million of debt reflects modest leverage. The stock: Balchem is up 3% in 2009, underperforming major U.S. indices. The stock trades at an expensive price-to-earnings ratio of 23 and offers a dividend yield below 1%.