Unfortunately I don’t think Verbatim manufactures any quad-layer, so Sony was the only real option for 128GB disks.

Furthermore, M-Disc is still very pricey per-GB, and their non M-Disc BD disks aren’t price that much better. I’ve also recently got a spindle of Verbatim BDXLs that every single one would fail to either write or read at the layer transitions, so having a single option here is already proving to be painful.