Center, center, center
I am a highly dedicated paper puncher. And I am going to tell you it all depends on your eyes and the target.
Folks who shoot the 6 OC position in high power rifle generally use a thin front sight. The sight picture looks like a popsicle. I used to use the 60c sight picture standing even though I used a wide post. You can train your brain to pull the trigger just when the post touches the bottom of the bull.
With a 6 OC hold, you have to remember, did I put the target in the middle of the aperture, or did I put the post in the middle of the aperture? You will see some horrible vertical stringing when people forget. With a center hold, every thing is center, center, center.
Folks who use the center hold or flat tire hold use a wide post. Something that sticks out of the target. I use this hold from 200 yards to 600 yards. I like it as I just push the sight up until the target seems to be getting smaller. I also like it as I don’t get my sight picture confused. Center, center, center. Everything in the middle. Can’t forget.
I was squadded once with the Marine High Woman shooter at Camp Perry. Nice little girl. She used a standard service post. It covered the whole target frame. She just centered the bull on top, pushed it up, and stopped when it looked like it was in the center of the frames on the left and right! Worked for her.
The NRA pistol target bull is so large that you can only use 6 OC. Otherwise your post disappears in the black. I figure that target was developed when revolvers had real thin front sights. Like Colt New service or colt single action army pistols. Bullseye pistol has not changed much in the last 10,000 years.
Now, if I was going after Deer or something, I would use a 6 OC hold. When you have an indistinct background, it is probably better to have your point of impact just a little above your aim point.