I was planning on placing the LR on either side of the TV and the center below the screen (roughly at hears height)
IMO you could probably go with either a horizontal or vertical center then. Things I would consider are what your primary use will be, how close you will be sitting to the screen and how far to the sides the widest seating will be.
IMO horizontal center speakers can create a better “wall of sound” blending better with the mains which I find works best for movies, TV and video gaming especially if sitting close to the screen and if the L/R mains are spread out wide.
IMO a vertical center will create more precise imaging for vocalists and instruments when listening to well recorded music, but if the L/R mains are spread out wide and you sit very close I find that the center can draw attention to itself separate from the mains form movies which can be distracting. OTOH if you have people sitting far off to the sides especially near walls I find that a vertical center sounds much better far off axis horizontally especially with a wall nearby the seat.
In your case if you put all the speakers near the TV they would not be what I would consider spread wide apart.
IMO aesthetically the best look would be as tom suggests to use M22 mains and a VP100 center based on how you say you would position them, or M22 mains with dual over/under M2 centers.
Cheers,
Dean
