Lol, Zayn by far. #1 single and #1 album, Taylor feature with a song on one of the biggest movies/franchises at the moment, successful book, getting into the fashion world, high-profile relationship, becoming a business man.
Louis single basically tanked everywhere but in UK, Niall's single is relying on discounts but it's local af + it's flopping on views/streams, a non-event
Liam will bomb too, he's not charismatic and if that snippet he posted on his insta the other day was an indication of the direction he's going, then goodbye
Harry can be the biggest member but we don't know yet. Let's wait until he releases his music. But so far, Z is the Beyoncé/Cheryl/JT of the group.