My tirade below can be summed up as, "Shoot raw and play with the default settings in a post-processing application to get the photos 'right'. You can also shoot raw and JPG in camera then play with the camera settings to produce good JPG but retain the ability to go back and try something different."
The color space you choose affects your JPG and TIFF files created in-camera. It doesn't affect your raw files except that Nikon NX will read the settings as defaults for display and processing. Shoot raw and don't worry about the setting.
If you shoot raw + JPG then sRGB is nice for web and email. You can also change picture controls to something like vivid (monocrome?), more sharpening, and play with contrast to get your look. The iPhone makes nice photos but it adds a bit of saturation so isn't 'correct'. Film never got it 'correct' either. Shooting raw + JPG gives you the ability to create pretty darn good photos right out of camera while holding the digital equivelent of an exposed, undeveloped image on film. You can post process that any way you want as often as you want.
I recommend shooting raw. As if that wasn't obvious before. I wish I could go back to my early digital years and get myself over to raw processing on all my photos.
I use Lightroom and bring in files with default settings. That's good enough for 99.x of my photos. Think of it as getting film developed and printed at the local store. In a few special cases I post-process with adjustments.