Nick:
Great question!!!
Hope you compile the answers.
My two cents worth (probably more than 5, sorry)
Seats that are comparable to a high end sedan.
Climate control that works automatically
Engines and transmissions that are useful pieces of metal into which one puts in fuel and gets all the power one needs
Well thought out procedures for profiles like Category A that don't scare the passengers or spill their martinis
No vibration or noise issues
True zero-zero capability (approach to a hover IMC like what you showed me several years ago)
Flight controls where the pilot doesn't have to supply the right mechanical characteristics.
Good luck!
Shawn