If I were to chose between Arena, Cosmos, and Saveeit, I'd chose neither of them.Arena — great at networked thinking, yet lacks inclusivity in terms of free tier and payment options.Saveeit — same without strong networked thinking.Cosmos — the most generous and most visual. IMHO

Yes, absolutely. My mind is a cool thing, I tried it. Personally, I would want something between cosmos and arena. Good design, less centralized and more independent builders, and a generous free tier. And a thing that would play a social glue role as well. Just a little)