They're the same drive (Asus slapped its badge on the BH16NS40), and nearly the same firmware, save for the fact that the Asus firmware will automatically perform bitsetting on DVD+R/DVD+R DL (if that's a feature you need). LG has provided a few firmware updates, but I think the Asus is still on an older version. But that's about it.
So whichever one is cheaper, go for that. If they are the same cost, go for the original LG branded drive.
That said....I don't know if any quad-layer BDXL media exists in a widely-available form, so you should probably expect to actually purchase triple-layer BDXL (quad layer: 128 GB; triple layer: 100 GB).