One Direction's “One Direction: Where We Are” use to hold the record for an event cinema admissions record but that's not a thing anymore because BTS now holds that record. Their "Burn The Stage: Movie" has recorded 1.2 million admissions.
What's even crazier is that the movie was only shown in 2,560 theaters and has brought in $14 Million! They even managed to break into the Top 10 in the US bringing in #3.6 Million.
So at this point it would be safe to say that the BTS Army is stronger than Directioners. Not only here in the US but Worldwide. If there was a ranking system for fan armies, I'd say that the BTS Army is the biggest.
And as a special treat for the BTS Army - I added the video for "Waste It On Me"