Despite a flock of investors buying up South Florida homes for rental property profit, the market ranked lower than eight other Florida regions for the best place to purchase single-family rentals.Nationwide, Palm Beach, Broward and Miami-Dade counties also failed to place in the top 20 best investment areas for rentals, according to a RealtyTrac report to be released today that measured estimated profit by comparing home sale prices and monthly costs with average rental rates.Port St. Lucie, Orlando, Jacksonville, Daytona Beach, Tampa, Lakeland, Ocala and Palm Bay all earned spots in the top 20 list, which ranked New York and Northern New Jersey as the best place in the nation to earn rental income on a single-family home. Los Angeles was second, with Chicago taking third place.