It will be hung at eye level, so I'd go with the entire wall space.

I would centre on the entire wall space. Centred on the counter would visually narrow the space

I thought I would prefer centered on the wall from the bar over, but after I did a mock-up, I prefer centered on the wall. My only concern is if it is too close to where someone sits, could it be knocked?

It's possible it could be knocked, but I would still center it. To my eye it looks odd not centered.

Wow thank you all for the advice! The visual really helps. I agree centered in the wall looks the best.