If I became an idol because I want to have a productive, enriching and varied career in entertainment, I'd pick Red Velvet: I would have a career in k-pop but also an individual career that encompasses not only music but other activities like acting, musicals, etc too with a solid foundation to continue my own career after the first 7 years.
If I became an idol because the glory, popularity and success of it all appeals to me the most, I'd pick Blackpink. Lots of spare time where I can do whatever I want, all kinda events I can visit as a vip, and still be famous and successful.