It's just a general observation but I've noticed that YG & SM have different approaches when picking a main vocalists in their groups.

For SM, it's all about vocal range and technique. The majority of SM's main vocalists (Changmin, Taeyeon, Baekhyun, Jongdae, Kyungsoo, Kyuhyun,Wendy, etc.) have strong voices and SM loves showcasing it by performing an overwhelming high note in their songs.

While for YG, it's about your vocal color. Best example would be Park Bom.

Bom gets tons of hate for her singing techniques and sometimes, her unstable voice when performing,but the reason she's the main vocalist is not because of that (Minzy is a better singer than Bom, and we all know it) but it's simply because her voice stands out and has an individual sense in it.

same for Kang Seungyoon (WINNER), LEE HI, Taeyang (BIGBANG) & Junhoe (iKON).

YG's vocals are mainly recognized for their distinctive voices while SM has a knack for picking idols with strong and stable vocals