Research firm Stifel started coverage of several amusement park operators with Buy ratings, telling investors that SeaWorld (SEAS) should benefit from its strong management team, while Six Flags' (SIX) valuation is attractive.

SEAWORLD: Analyst Steven Wieczynski says that the stock has a better risk/reward ratio than any other theme park name he covers. The company's new management team has "considerable regional theme park operations experience" and should be able to execute on its turnaround plan, the analyst believes. SeaWorld's ability to expand overseas without investing a great deal of money is "underappreciated," according to Wieczynsk, who set a $23 price target on the stock.

SIX FLAGS: The company is a "best in class" theme park operator, according to Wieczynski. Moreover, the stock's valuation is below the five year average, even though the company's earnings before interest, tax, depreciation and amortization growth should accelerate through 2019, he wrote. The analyst also says that Six Flags' international licensing business is poised to accelerate over the next one to two years, enabling the company to carry out its "capital initiatives." He placed a $70 price target on the shares.

CEDAR FAIR: Stifel also started coverage of Cedar Fair (FUN) with a $78 price target and a Buy rating. Wieczynski says that the company has delivered consistent results, while its planned utilization of additional land should enable its EBITDA growth to accelerate over the longer term.

PRICE ACTION: In morning trading, SeaWorld rose 1.5% to $17.25, Six Flags gained 1.4% to $62 and Cedar Fair advanced 1.6% to $70.33 per share.