My kid is wanting an RX78 with a core fighter that actually fits inside the torso of the suit. He's been interested in this for two years since his first kit the BB RX78 with core fighter. He's done 3+ HGs on his own and his birthday is coming up so I'm shopping for his request.
So not wanting to go too expensive I'm conisdering MG, MG1.5, MG2.0, VerKa, and RG. Whew. Durability is more important than badass looks at this point. Any thoughts?
While I haven't built the 1.0 or the 1.5, I have built the old 1.0 GM that it shares a lot of parts with. I would avoid those as a first MG as they will be disappointing compared to a modern HG. This doesn't preclude building them at a later date if found super cheap in order to understand how MG have evolved but this is a completely different matter than the one that occupies you right now.
The thing about the 2.0 is that it has the "anime" proportions and surface detail. Personally, I'm not in love with how it looks but the build is supposed to be solid from what I heard. Relatively modern (2008) but on the upper price range of what you listed.
The Ver.Ka I also know it indirectly by building the GM Kai which it also shares a lot with. It's not a particularly modern kit (2002) but it's fairly decent and it is quite affordable. The looks of the kit, once done, are rather attractive in my opinion.
The RG, I'd say avoid, seeing as durability is one of your prerequisites.
I guess your list omits the One Year War MGs because they don't seem to feature a core fighter that fits the torso. I like how it looks (more the animation color version than the game color version) and being from 2005 it's decent without being pricey but it does not fulfill the main premise of your question.
The 3.0 and The Origin are slightly more expensive than the 2.0 but not much more. If I had to choose looks and interesting build I'd go for the 3.0 if the price isn't outside of the range you had in mind. As for it being slightly too complex, I don't think there should be anything that cannot be tackled with a bit of patience and asking for your help if a roadblock arises.
TLDR: 3.0 if not outside the price range you had in mind. Otherwise, Ver.Ka for a cheap, older alternative. 2.0 is a middle ground if OK with its looks.
depending on how old the kid is
I love how in any other page of this thread this would be a typo. Age is a factor when building kits but is it much more complex than the RG?