A Roomba. Set & forget.
I'm a noob but I can tell you what I have learned. I like simple green - spray it on the rag not the pinball's surface. It is very effective at gently lifting dirt (forget the stuff about the machine being worried by water etc - it's been through (or will go through) many years of fluctuating humidity, far worse for it than the occasional clean. It can be used on playfield (not soaking of course) & on the cabinet. For hard playfields I like simple green, Novus 2 then Novus 1. For plastics Novus. For metal Autosol. I'd be surprised if there's any product that does all parts - but IMHO Simple Green may go close. Some prefer Nifti.
Edit: Just adding a disclaimer this is on newer Bally/ Williams games (which are built like tanks). If you are cleaning a Stern please be careful as a light breeze can lift colour from the machine (or so I've heard).
