After rewatching the teasers, I think my ideal lineup for Sixteen (I refuse to call them Twice) would be:
Vocal line: Jiwon, Jihyo, Minyoung
Dance line: Momo, Mina
Visual line: Sana
There are supposed to be 7 members, right? I don't particularly like any of the others (I don't even really like Sana but she's pretty and can sort of hold a tune so) but I'd probably take either Tzuyu or Dahyun. If JYP made it six members, which would make a lot more sense, that lineup would slay.
