While it's not the most important part of the lift, I always champion the case of a neutral neck position during the deadlift.
There is absolutely no reason to lift your chin up when you're bent over. This is the equivalent of looking straight up at the sky while standing upright. It's not a natural neck position, and when your back/neck is already being placed under heavy tension, this is the wrong time to start getting creative with your neck.
My best tip; look down when bent over. Look straight ahead at the top of the lift. To answer your title: yes. You should keep your head in one line with the body.
People will counter-argue with "I want to check out my form in the mirror".
I will counter-counter-argue that you can do this without pointing your nose at the mirror. You only need a very minor head-tilt to see yourself perfectly in the mirror.