I really prefer having the monitor slightly on top of the housing with a 45° angle.
When the monitor is at the back perpendicular to the housing (like on pretty much all splash / surfing housing), at some point, underwater, it's too much effort for my neck, back and arms.
But I also think the closest to the housing, the better it is. The picture of the Nauticam GH6 housing quite scares me...
