The user has more effect on the final product than does any of the top-ranked digital camera file converters and developers. Music isn't about the instruments, though good instruments will allow good musicians to make better music. Make yourself into a good instrument, first, then and use the best instrument at hand.
Between LR, C1Pro, and Aperture, the choice does not come down to _image quality_; it comes down to ease of use (user productivity), additional functionality (as a DAM, C1Pro is poor, LR is good, and Aperture is excellent), intangibles such as the user's comfort with the interface, and tangibles such as "Does this program run on my OS?".
I don't know about DxO Optics. I assume it's comparable*. (I've had no reason to look into changing my workflow).
Try them all; buy the one you like to spend time with. Learn
why the tools are programmed to work the way they do, and what they do at the pixel level, in addition to how to use them.
* However, I would steer far away from anyone and any company that uses the word "magic" to promote digital camera file developing software. The following, currently
on DxO's front page, is BS afire:
The thing I really appreciate most about using DxO Optics Pro is this 'lighting engine'… and suddenly the pictures that were throw-away before just blossomed. If you can magically have some way of eliminating all the flaws in your camera and in your lenses, and instantly correct all of that, so that the starting point of your pictures is 15 to 50% better before you do any kind of editing to them at all, why would you not do that?
- Ian Coristine - Photographer | Canada