Chain lube, it penetrates well, stays where it should and is resistant to being washed off. I use stacks of it on anything that moves under a Cruiser or the trucks at work, also in box sections, behind mud flaps and anywhere needs protection.
Everyone to their own on this though, its what works for you in your situation, the only thing necessary is regularity.
I lubricate the hinges/locks etc at least once a month, people I know have never lubed the hinges etc during their ownership.