I'm @a8m's co-founder and also a maintainer of Atlas. I don't have an exact feature comparision but Atlas (and esp the Postgres driver) are heavily maintained with advanced features like views and materialized views (functions and procedures coming up, followed by triggers and more).
What features specifically are you missing in migra? Perhaps we can prioritize them. Also feel free to join our Discord https://discord.gg/zZ6sWVg6NT
https://github.com/djrobstep/migra
I'm asking because, although migra is excellent and there are multiple migrations tools based on it (at least https://github.com/bikeshedder/tusker and https://github.com/blainehansen/postgres_migrator), issues are piling up but development seem to be slowing down