Antimony [1] is stable and user-friendly. You can get started without knowing about the underpinnings, just by connecting predefined shape nodes into a graph – basic modeling is possible with just the mouse, as shapes can define handles in the UI. Using Python for scripts is also a bit more accessible than Scheme. The downside is that hacking raw shapes is less pleasant, because they're defined as strings implementing a DSL. Developing on Antimony is also slower – much of the code is UI and glue to attach the geometry + graph engines.
Ao is more experimental and unstable. It's much lower-impedance for folks that want to work directly with f-reps, but doesn't have a click-and-drag UI with which to get started. The geometry kernel is also newer than Antimony's, and has slightly better performance. From a development perspective, I can play more easily with new algorithms without a cumbersome UI.
For folks that aren't as comfortable with coding, Antimony is the right choice. For f-rep development, Ao is the right choice. Otherwise, it's a matter of personal preference.
I wouldn't say Python is more accessible. Considering this will be used by first time programmers who just want to design to print, and given that Scheme has less semantic baggage than Python, I'd wager that it's a better choice. Also, the data-driven nature of things is more natural to manage in a Lisp dialect.
I think it'd be killer if you could combine the user interface of Antimony with the same inspectability Ao. What would it take to achieve an Antimony-like UI on top of Ao?
I'm currently writing a toy library to play with hierarchical graphs – if Ao is a minimal implementation of Antimony's CAD, this will be a minimal implementation of the graph engine.
Beyond that, it's a small matter of programming – I'd want to find a UI paradigm / library that's less cumbersome that Antimony's, as the UI programming adds a lot of impedance to development.
Ao is more experimental and unstable. It's much lower-impedance for folks that want to work directly with f-reps, but doesn't have a click-and-drag UI with which to get started. The geometry kernel is also newer than Antimony's, and has slightly better performance. From a development perspective, I can play more easily with new algorithms without a cumbersome UI.
For folks that aren't as comfortable with coding, Antimony is the right choice. For f-rep development, Ao is the right choice. Otherwise, it's a matter of personal preference.
[1] https://github.com/mkeeter/antimony