Yeah it was Somi and Sejeong but I thought Doyeon was popular because of her body and face. I might have remembered wrong And I put Yeonjung in the category because Cosmic Girls are successful but not super successful like the others and she still has potential to become more popular with more solo and acting work
Overall I think this thread was really accurate. And understand why you put Yeonjung in the category you did.
Doyeon was the least popular out of the visual-line. Chaeyeon and Jieqiong were the two main visuals of IOI (tho I always thought Doyeon was the prettiest) and Nayoung and Somi received more attention for their proportions than she did. She still got a lot of praise for her visuals and was clearly a favourite with fashion and beauty brands but no, she wasn't one of the main members popularity-vise.
Somi and Sejeong were ofc the most popular in the group. After the two of them Chaeyeon and Yoojung followed. Then it gets trickier but I'd probably put Jieqiong in 5th place and Sohye in 6th. Making Doyeon the 7th most popular.