I don't necessarily mean the most successful and of course only your opinion.
BTS = 2016-2017. Wings era made me a Army. Even Dynamite and Butter can't come for this experience.
Blackpink = 2018 and 2020. D4/ForeverYoung and The Album. Can't decide.
Red Velvet = 2017. I just say Red Flavor
SNSD = 2009 and 2012. Gee and The Boys. Can't decide again.
BigBang = 2012 - wow, fantastic baby.