Like most things in life, it depends.
Do you have a room in mind, or is this hypothetical?
Consider the storage needs, space available, wall and tv relative sizes/ proportions, style of the room in general..
A unit of some sort often gives a more balanced look. wall mounted tvs can be paired with a unit too, without resting on it.

I like wall mounted with a cabinet underneath to hide all the stuff and wires and I do not like that cabinet to be as high as a regular console it raises the TV too high for proper viewing height. The best is placing the T.V so that the center of the screen is at eye level when seated.