To me, the One X and One X+ have a better dynamic range straight out of the camera while the One tends to be a bit sharper over all with a bit better detail.
I do photography part time so I am used to post processing 100% of my photos, first in Lightroom then in Photoshop.
If this was a real camera, I would prefer the One. A bit of PS post processing gives out very good results.
It isn't a camera though, it is a phone. People want to snap a shot and share it with others, without a need for post processing in Snapseed, Photoshop etc.
So to sum it up: I think the One has a better camera but the One X and One X+ are better camera phones.
If that makes any sense.