Vocals for me. Yuna and Ryujin are some of the worst subvocalists in kpop, I know most subvocalists are usually bad but these two are just beyond saving. Yuna sounds like a 10 yo old kid, and Ryujin is always trying too hard.
Yeji's solo is arguably their best work to date and it's because it didn't involve the 2 non-singers. Lia and Chaeryeong have pleasant tones but the song selection combined with their lack of skills just renders it all useless. Itzy always had weak vocals but they used to be great until Sneakers. Idk what happened after that maybe its because of Nmixx (another JYPE GG) and other powerful vocal groups like aespa and BaeMon debuting that people have started noticing and calling out Itzy's terrible vocals more. And they are now at a point of no return.
Yuna last few years get rid of that young childish voice and improved while others are pretty much same.
And even in old songs Yuna's cringe childish moments were rare compared to Ryujin fry that killed vibe of most songs for me.

we cant be friends 