Well, here's my experience with Nikon.
In April, I bought (pretty much in a knee jerk reaction to a Craigslist ad that seemed like a good deal) a Sony Nex F3 with a kit lens. I figured I'll see what all the fuss is about, and may be keep it as a small backup camera for travel since my old P&S finally died.
Within a month, I sold all of my Canon gear (well, one lens is still on CL), and got some Sony E-mount lenses and old Minolta MD manual lenses. For variety of reasons, but the main ones were better DR and low light performance, smaller size, and ease of use with manual focus lenses.
Last month, I spilled some water on the camera & it killed the AF on camera (everything else works fine). The bag of rice trick didn't help, I must've fried contacts. So, a bit dismayed at Sony for letting this happen (yes, my fault, but I had worse things done to my Rebels without any issues) I started looking elsewhere. I was always curious about Nikon, and according to DxOmark, D5200 had even better DR and ISO performance than Nex. So, I figured, I will trade the small size of Nex for (supposedly) better ruggedness and wider lens selection of Ken Rockwell's favorite brand.
To be honest, I was very disappointed. I got a two lens kit from Costco, and no matter what I tried, the shots were soft. Even at f8 and above, with flash freezing motion. Even compared to the couple dozen shots I did this January with an old Canon EF 28-90 which was supposed to be a total dog. I did a search and found that complaints about D5200 softness were common.
The SOOC JPEGS were also a disappointment. I don't like Sony JPEGS because of very high NR (which is too high even at low setting) that destroys shadow detail in low light shots. The problem was, no matter what settings I tried, D5200 had very dark shadows in low light jpegs (at least I couldn't make them lighter without blowing highlights). So it still required raw processing to get properly exposed, good dynamic range shot. I kind of hoped to get better SOOC JPEGS for immediate sharing. I'd say that Canon JPEGs are still the best overall (color, sharpness, good detail if properly exposed), Sony's are 2nd (good DR and sharpness, but colors tend to be reddish and over saturated, and NR is heavy handed), with D5200 being soft, with dark shadows and yellowish / greenish tones. It is possible that this could be fixed by customizing output settings, I did try playing with them but didn't get far.
Finally, the menus... I think it was the worst menu system I ever saw, and that's coming from a guy who uses Sony 
. At least, Sony menus are poorly arranged, but very self explanatory (and can be customized). Nikon menu looked like a total cluster you-know-what, by comparison. Again, it can probably be fixed to some extend by customization.
In the end, the soft photos and overall IQ being - straight out of camera - below what I could get with Nex prompted me to return the kit to Costco and order Nex 6 from B&H.
I am sure Nikon is a great line of cameras, and I am sure if I got D800 I wouldn't put it down. But, I need a small camera with great IQ, and based on my experience (granted, short and perhaps one sided) if I ever go back to DSLR, I'd go with Canon before I go with Nikon.
, I end up using SU-800 more.
