DXO mark means nothing. They take their objective tests and interpret them in completely subjective ways, all (as it would seem) on Nikon's dime. Super biased, all rubbish, especially their ISO scores. Canon should be top of the mark for every camera they've put out in the ISO division, right next to Pentax, and Nikon and Sony should be right in the bin every time. But it's absolutely the opposite. If you've ever seen the DPReview studio comparison tool, I highly recommend cranking up the ISO on there and seeing for yourself what I'm talking about. D5200? Rubbish. D800? Rubbish at anything above or below ISO 200. 5DIII? A f@ck!ng mint. DXO scores the opposite in every case.
Can't agree with you without knowing specifically WHY you think this. Not sure I would if I did, I don't care for the one-number DxO score either.
Have a close look at the full test results for each camera sensor and compare those. To start with, look carefully at the full range signal to noise tests and you'll likely see results closer to your expectations.
I'm gonna start this off by saying I was always a journalist first and a photographer second. Deep, borderline-invasive research is in my bones. I've definitely combed DXO's tests and scores thoroughly before any camera review I've written, and often something seemed a little off.
The whole thing was exacerbated when I helped start up this large-format print shop up north http://www.counterfeitink.com
(wait till the third banner to pop up on the homepage and you'll see my ridiculous cigarette-bearing face top left on the Canuck-style $5 bill) and got to see the results of all these cameras first hand. I was the one optimizing photos for print, doing the upsizing and re-sharpening, and priming the finished prints for delivery. When a camera that prints a perfectly sharp upsized landscape print at 4x8' with no noise or lack of dynamic range scores 8 points lower than a camera with no details in the shadows, noise at near-base ISO and smudgy-looking detail only a touch above its native resolution, there is a fault in the system.
I've since left that print shop and started up a medium format photography studio, specializing in large prints. I run photography lessons, edit other photographers' photos and I still write the occasional review. I know using Phase One — with even just the Schneider kit lens that's sharp enough to shave with — is like touching perfection, because it's my main setup on the job. I know where "the bar" is set.
I can't emphasize this enough: You can read all the books and studies you want on Irish boxing but it doesn't mean anything until you've been in at least your first handful of Canadian bar fights. Having used, tested and reviewed a huge range of these cameras, having made large prints for every soccer mom with an SLR, having cycled through my share of gear and having cycled through my share of assistants with their own wide range of cameras and lenses, I know an 85 vs. a 60 on DXO means literally almost nothing when you've really put a setup through a hard day's work.
I'm not asking anyone to take my word for it, either. Again, check out the DPReview Studio Comparison Tool or better yet, put Best Buy's über-flexible return policy to work and try a few out for yourself, side-by-side and you'll indefinitely come to the same conclusion.