Re Beterbiev, note also that he missed the chance to fight and perhaps beat Kovalev and Ward and maybe even Stevenson as well. Not really his fault as it's mainly due to Michel deliberately holding him back + Ward got to a declining Kovalev first and then retired. But, those names would make a HUGE difference when considering ATG rankings. If he had them + Bivol & Benavidez then he would have legitimately dominated for 10+ years and beaten top p4p / HOF - level opposition while doing so.
Galaxy never unified and didn't fight any of top fighters of his era very padded and overrated and some shady stuff going on in Thailand I heard. If Estrada beats Ioka I would rate him above Galaxy clearly.