I think GD's catchiest songs are not necessarily/do not necessarily have to be their strongest songs (lyrically or musically). Case in point: stuff like KYE or Chump. They aren't the peak of Billie's songwriting career, but they sure as hell damn rock.
Speaking of KYE: after hearing how they play it live, I'll never look at the album version the same way again. KYE is one of those songs that are better when you play it hard, fast, and raw. I just felt the album version was a tad too slow - not to mention the instruments are kinda weak. And oh god Billie's vocals. (Honestly, I never really liked how Billie sounds in 21CB.)