Weird... I'd have thought the basics should at least be available in different scales. But it's probably a popularity / sales numbers thing. Maybe I'll wait for the HG then. Anyways really appreciate the help :)Right now there are no MG Zakus from the Origin, neither released nor announced AFAIK despite there being a lot of different HG Zaku variants from the Origin.
If having a Zaku that follows the Origin designs in order to partner it with the RX-78-02 is a priority, then I'd get the upcoming HG.
HG will always give you more variety than MG and the number of Moblie Suits that have an MG but not an HG are relatively limited exceptions.
I mean, we are in 2020 and from the original 4 Gundams of 00 only the third has just been announced with the fourth still unconfirmed while the amount of HG00 releases is enormous. There are some other 00 Master Grades but for the longest time it was mostly Exias and 00 Raiser variants.