For those that are still sceptical about Omega's heavily implied superiority over Base/SSJ/SSJ2/SSJ3 Gogeta, here is the quote that @Captain Cadaver referenced:
Even w/o that quote the same conclusion can be drawn, as the GT Perfect Files state that SSJ4 is a potential unlock; w/ Gogeta being the fusion of two Saiyans that regularly received big gains, it'd only be natural for him to have huge potential. Additionally, the GTPF state that SSJ4 Gogeta is
several dozens of times stronger than a regular SSJ4, implying that the power gap between Omega and SSJ4 Gogeta isn't double figures.
Omega stops at SSJ4 Gogeta.