For this article right here, the metric we meassure as popularity is views on youtube.
Blackpink and BTS are the most popular kpop bands, Blackpinks is a girl group and BTS is a male group.
Blackpink has several musicvideos with extremely high views, two of them are Kill this love (more than one billion views) and 2020 music video that is 4-5 months old How You Like that (640 million views).
Bts has several music videos with extremely high views, two of them are 2020 music video Dynamite (588 million views) and DNA (more than 1 billions views).
Other kpop groups, doesnt have as many youtube views as Blackpink and BTS.
But there are other kpop groups that get over 100 millions views in their musicvideos like Twice.
Source for the image : https://kbizoom.com/