Difference between Pix shells?

I'm considering maybe getting a Pix (still thinking), the regular one (mostly because I don't really like the party shells, and I'd like the opportunity to raise an Awamokotchi)

I really like the green one but it's soooo expensive where I am right now... I would get a different one, but I'm not sure which. I've heard that the pink and purple ones somehow have worse battery life and buttons than the green/blue? Is that actually true? I use rechargeable batteries so I'm not really worried about being wasteful, it would mostly just be annoying to charge them often. I can definitely see the buttons being frustrating if they're as bad on some models as people say though.

Thanks in advance!