While there isn't an official ranking or measurement of lip thickness among the BTS members, Jimin is often cited by fans as having noticeably full lips.
It's subjective and based on individual perception, but the perception of Jimin's lips being particularly prominent is a recurring observation in online discussions. The quote from Quora emphasizes this sentiment: "Jimin's lips are absolutely iconic...it's pretty uncommon for a man to have lips like his."
Therefore, based on fan opinions and general observations, the likely answer is Jimin.
