Well, not the floor. How much space do you have above the screen? In my view above the screen is the best location for a center channel. Most heads are towards the top of the screen. So that get the heads and speakers closer together in most cases. In addition it gives the best room coverage.
Like this:-
The front of that speaker slopes towards the listening area, and the driver is coaxial and right above the screen.
If you have space above the screen and the ceiling, that is your best option.