To me, ShotPro is not only the easiest previs out there, but the easiest 3D software I've ever used! I'm thinking the possible features could make ShotPro the best CGI & compositing software:
1) The ability to create 3D models in the app (Hopefully photorealistic?)
2) The ability to animate more figures of an object (Fingers & limbs on characters, Car doors & wheels, etc.), as well as rigging objects & models
3) The ability to import videos to run the CGI on top of, along with features to improve textures & lighting to the composite
4) The ability to create 2D animations along with the Text & Write addon, with an option to create 2D annotations & drawings into objects in a 3D environment
5) Motion capture for characters
6) Possibility of photorealistic graphics?