I will not put them in the same level with Bp, Twice and Red Velvet especially now because the gap is too far.
They're under those three, at the same level with Oh My Girls now and GFriend.
That's a you problem then.
GFriend is disbanded and had a one year peak, and OMG really has one hit album (Nonstop/Dolphin)
Mamamoo had chart topping hits for nearly five straight years.
Mamamoo has been at the same level as BP, Twice and Red Velvet for much longer than they haven't, and off the top of my head, they've had 5 solo title tracks, 1 a collaboration with Loco, top the digital charts in Korea.
Name me another girl group that has more. I'll wait.