Both have their moment on different era (gfriend on 2016-2018 while OMG on 2020-now)
OMG have bigger album sales, GFRIEND have slightly better popularity international wise
in term of hit song both have national hits (MGT,Rough and Nonstop,Dolphin)
so who deserve to be the fifth biggest GG after BP,TWICE,RV and MAMAMOO?