First off is the Blitzway 1/6 Ecto.
The other is the Eaglemoss 1/8 Ecto.
From what I've gathered, the Blitzways replica will be made mostly of plastic whereas the Eaglemoss replica will be primarily metal. I have no first-hand experience with Blitzway products but I do have experience building one of Eaglemoss's other large scale cars so I'm familiar with their quality and the partworks subscription method they use.
I'm curious which replica (based on the early prototype photos available) look more accurate? Ultimately, I imagine both will have inaccuracies so I'm lean toward doing the partwork build since it's easier to make mods before assembly than it is having to tear down a prebuilt.
I'm certain neither will have satisfactory lighting so I'll probably end up making a small arduino board that will operate all the siren lights.