Frankly, IVE is not in the top tier in any category. Vocals; they barely sings live and when they do it sounds horrible. Their main vocals, Yujin and Liz, have lovely voices but in terms of singing they won't even make it as main vocals if they had debuted in the 2nd gen. Dancing; their dancing skills are just so-so and they also have problems with synchronicity and lazy dancing. They also don't have a good enough dancer to be called a main dancer. Visuals; they're effin beautiful but there are tons of groups in the 4th gen with higher or at least same group visual level as them. Just off the top of my head there're STAYC, woo!ah!, MAJORS, ICHILLIN', Weeekly, Fromis_9, ALICE. Songs; though their songs have catchy hooks they are also bland and vocally unimpressive. Though I do concede that Rei is a good rapper. Contents; I've watched all of their contents on their channel and it's just really flat, awkward, and kinda plastic.
I'm happy for them that they are successful but it's curious what really catches the attention of kpop fans. Obviously it's not always talent.