Okay so.
Kinda want to discuss avatars:
All three seem to focus on different Aspects of Goji, and I think it's important to note that these aspects probably merge together. Given the presence of both SP and Shin, I wouldn't be surprised if big G had some level of adaptive ability.
I think that's important to note because that means that Despair, Evolution, and Nature are all different facets of Godzilla here. Whichever one we choose, the other ones aren't less true. It's just the facets that get represented in Taylor - or maybe what she subconciously feels most represents her, hence why Despair is probably an option.
Despair then focuses on sheer destructive power, Godzilla as a Monster. No bonuses to stats, but the ability instead makes it easier to grow, sacrificing something more esoteric for further strength. I find myself reminded of the quote regarding godzilla about how the tragedy of monsters is that they are born to strong and heavy to be able to interact with our world, and I think this form is kind of the embodiment of that. That strength and power can be useful, especially in a world like this, but you also become constrained by that strength.
Evolution in some ways is the middle of the road option. Middling stat boost, middling prowess, and an ability that's useful, but isn't quite as long term impactful as Despairs. Instead the focus seems to be on Godzilla as a Higher Dimensional Being, and the ability to comprehend some of that. The downside being that its growth might be slanted heavily in that comprehension over combat ability - the higher dimension stuff is important, but the three we know is where all our stuff and Dad is.
Nature is probably the most esoteric of them, Godzilla as a living Creature. It's got the largest stat boosts, but the way they're spread implies that of a thinking creature - tactics, hiding, and learning. It's prowess is the lowest, but it's intended to be applied in just the right way to have an impact. And it's ability is less immediately strong, but it also implies a connection to the world - whilst also allowing us to turn attempted sneak attacks or 'Nothing personel kid's around on our enemies, tying into that 'fight smart, not hard' mentality.
But regardless of which one we pick, the other two are still parts of Gojira, and I think that Taylor will need to spend time understanding them to truly find a kind of symbiosis with the King of the Monsters.