FBX camera support or the option to create and save cameras in Painter directly. The cameras are saved in the SPP file and provide reliable, repeatable results that can be directly compared for faster iteration and client review. Even final PR renders in some cases.
When multiple cameras are active in a scene the Iray renderer could offer a batch mode for unattended rendering of all active cameras.
Animation: Most of us here don’t need a timeline but turntable functionality with the options to either rotate the mesh or rotate a camera around a freely placeable null object would be amazingly helpful.
Camera support would be great, import from Alembic or FBX would be prefered as it would enable VFX to setup cams in a DCC like Max or Maya and then do TextureProjection and Painting in Substance Painter as opposed to Mari.
Would be one of the Features which lets Mari users switch over!