What's the BEST SOOC nikon dslr?

Is he staying DX or going FX?  What is the budget?  Infinity?

I like the "Sony generation" sensors and their output (the D5100/D7000/D600, etc) but that comes down to taste.  I'd get a D600 although that is similar to a D7000 with a FX sensor.  The D7000 is probably the logical DX choice but that's been ruled out.  So that would leave the D5100 as my choice as I don't think the D5200 is an upgrade.  Whatever he picks, make sure he turns up the default sharpening settings for out of camera JPEGs.  With the D5200 or D5100 you lose the motor for the legacy lenses.

I'd pick out what your contender cameras are, and then show him some photos.  See what he likes best.  Anything we tell you is just what we like and half of us are the RAW/tweak every slider in Lightroom crowd.