These two longtime giants in the suburban office market — Stern with Hartz Mountain Industries and Hersh with Mack-Cali Realty Corporation — are making the successful transition to multifamily. Who is more successful? It's hard to say, so we're letting them share the spot. "Manny is making more deals with more people. Even Mitch would admit that," said one observer. Another, however, leaned toward Hersh and his Mack-Cali REIT: "His acquisition of Roseland allowed him to become a major player right away.