Aftermarket Radio and Head Unit

I'm planning on updating my audio system and adding two 12"s in the back. However, I think I would need a new radio so I can add the 12"s and still have the rear door speakers active. That's just so I don't have to take the audio input from the rear door speakers and route then to the 12"s. Again, however , I would need a new head unit because the stock head unit doesn't just control audio, it controls the cars mechanical issue notifications as well. So here's my question, which head unit and radio system works the best together so I can still receive mechanical notifications and have a way to route audio input to some 12" speakers?

I'm also open to ditching SYNC and going with Android Audio.