While I agree with the other reply's "it depends" questions, at a high level there is one thing that I think applies pretty much whatever scope you're working o

While I agree with the other reply's "it depends" questions, at a high level there is one thing that I think applies pretty much whatever scope you're working on, with a few sub-points: - Find robust parts for the non-innovative aspects of your system (eg motor drivers) - ...with a standard interface (PWM/PPM, RS485, CAN, Ethernet, whatever) - ...hide that interface behind a simple software interface so that if you do have to swap to a different bus type you can do so mostly transparently - ...and don't reinvent the wheel if you don't have to. Once you have a set of proven parts with well-defined simple interfaces you can start treating those like Lego and mix and match to your heart's content.