BOSTON ( TheStreet) -- Lockheed Martin ( LMT), Southwest Airlines ( LUV), IBM ( IBM) and Chevron ( CVX) are among companies that offered the best 401(k) plans this year. BrightScope, a service that offers retirement-plan ratings and investment research, calculates its reviews with data from plan sponsors, the Department of Labor and the Securities and Exchange Commission. Its ratings system analyzes more than 200 factors and determines a score. Among criteria are plan costs, company generosity, participation rates, salary deferrals and investment-option quality. Atop the rankings, which were restricted to plans with more than $1 billion in assets, is Saudi Arabian Oil's program for American employees, which earned a rating of 92.9 out of a possible 100. It was followed by the United Airlines ( UAUA) Pilot Directed Account Plan, rated 90.6. Rounding out the top three was Wellington Management at 88.7. Among plan features and company incentives used in the ranking were company contributions, including matching, profit sharing and stock bonuses. Saudi Arabian Oil, for example, matches 100% for up to 9% of employee contributions. The plans with the highest company contributions were United Airlines ($37,069 per participant), Wellington Management ($18,679) and Nucor Corp. ( NUE) ($15,598). Those making the top 30 list have some of the lowest fees in the 401(k) marketplace. BrightScope's calculations include investment expense ratios and administrative costs alongside fund-level trading and transaction costs. Two of the plans on the list, those belonging to IBM and Exxon Mobil ( XOM), have fees of less than 0.3%. Fifteen plans on the list are under 0.5%. The average is 0.57%. The average participation rate among plans on the list is 94%, with Exxon Mobil obtaining 100%.