Compared to the returns of the Alerian MLP Index (^AMZ) and the S&P 500, Plains All American Pipeline (PAA 2.11%) did not have a great year. In this video, Fool contributor Aimee Duffy explains why, despite its unit price performance, Plains was one of her favorite energy stocks this year. Aimee also gets into why she thinks its performance will improve next year, citing the partnership's joint venture with Enterprise Products Partners (EPD 1.22%) as an example of just one contributing factor.