Chick-fil-A, the quick service restaurant chain specializing in all things chicken, has beaten KFC as the fried chicken king for a second time, according to Bloomberg BusinessWeek.

Data from food industry researcher Technomic confirmed that the Atlanta-based chain passed $5 billion in 2013, compared to KFC's $4.2 billion. Chick-fil-A first surpassed KFC as the top chicken chain in 2012.

KFC, owned by Yum Brands Inc., has reportedly been struggling in recent years. Chick-fil-A has held the lead because its locations are much busier, despite KFC being a much bigger chain globally. Chick-fil-A has only 1,775 U.S. stores compared to 4,491 KFC stores. Chick-fil-A restaurants are not open on Sunday due to religious reasons. 

According to Technomic, last year, Chick-fil-A pulled in $5.05 billion in sales and KFC brought in $4.22 billion in U.S. sales. Bloomberg BusinessWeek reported that Chick-fil-A can base some of its success on its breakfast menu. KFC does not have a breakfast menu.

Chick-fil-A stores averaged a 3.6 percent increase in sales over the prior year. This is compared with the two percent decrease for KFC. In recent years, KFC has struggled in sales, despite presenting new menu items like boneless chicken pieces and snack cups designed to fit in a car cup holder.

In addition to the chicken sandwich and waffle fries, which are the chain's most popular items, Chick-fil-A also offers a variety of wraps, salads and milkshakes that cannot be found at other fast food places, including peach and cookies and cream.

In an email, a representative for Chick-fil-A said the company was "deeply grateful" for its loyal customers as it expands into new markets. However, Chick-Fil-A has received negative attention from the media, due to owner Dan Cathy's Christian faith and personal views on homosexual marriage.