“Best” is relative to the rider, their goals and the specific equipment.
For a large display like a TV or monitor, I feel it’s good to have the center of the screen aligned with the “normal” forward looking position of a rider on the hoods (or whatever is your main position). Aim to have a similar body and head position as outside riding.
- For me, this is a 40" TV, about 2 feet in front of my head, and the center about 1 foot higher than my bars. I also tilt the screen back about 10* which makes it more “realistic” looking, especially when using first person view within Zwift or watching POV riding videos.
- We often see people with high mounted TV’s and I see it is problematic and awkward.
Here are a couple of shots of the my setup as it evolved:
Lots of examples and some discussion in the large thread below: