Millennials — increasingly dictating the health of America’s top brands — helped American Airlines topple Delta for the Fort Worth-based carrier’s first Full Service Airline Brand of the Year designation.

Dallas-based Southwest Airlines (NYSE: LUV) marks its sixth consecutive year as Value Airline Brand of the Year, according to new airline information from The Harris Poll’s annual study of brand health.

This is the second recognition American (Nasdaq: AAL) has received this year. Earlier…