Both the MyHolo's are indies now, at least afaik. It def isn't Hazard Hornet or Dokibird, and the NijiEN debuts crossed out a number of them. The four most likely imo are Bao, Miki, Ayane Ninomae and Namirin, the last of whom has gone on hiatus with monthly patreon streams. Bao is more speculation. Imo it's probably Ayane, but who knows. Bao and Namirin would also be good, and Miki would be a good fit for EN gen 2.
Channel links:
Bao:
https://www.youtube.com/channel/UCZQ7nZ8Lc7pslBN0gN1Jg0wMiki:
https://www.youtube.com/channel/UCRVYDlnhf6MCqbbf5-jjjsQNamirin:
https://www.youtube.com/channel/UCb-crO2ATrJsm253151B4VgAyane:
https://www.youtube.com/channel/UCk03zgqNZwy_CT-jDPS9vgw 