I think it depends on the person and what power setting they like. However, your scope should not change POI with the different power settings. If it does send it back and get it fixed.

I like to shoot at 9x when target shooting at 100 yards. I've got a few friends that also do. Then I've got others that like 5x or so at 100 yards. I'm starting to get more to where I like the lower powers also. However, it's hard to see the bullseye all that well to me and hold the crosshairs on it at 100 yards without zooming in at least some. I'd try out different power settings and see which you prefer. At shorter ranges I like 4-5x for sure.