<p>I'm a high school senior who has taken photos as a hobby for about 5 years now. I've gone from a film camera (Nikon FE2), to a mirrorless (Sony NEX-C3), to a DSLR (Nikon D90). I've been using my D90 for about a year now and I'm quite committed to the Nikon brand (with a solid set of pro-grade lenses). Recently I've been getting more and more paid work and I feel that it's time to go for a full frame Nikon camera. All my equipment has been bought used and whatever full frame camera I decide on will also be purchased used (I can't afford new and I don't see much reason to buy new aside from a slightly shinier product and a warranty).<br> What Nikon FX camera is the best performance for the value? And to be more specific, most of the photography I do is sports (softball, dogs, horses, racing, etc.) and portraits. I've considered the D700 and D600 mostly, but aside from a few slight differences (sensor, AF, frame rate), I can't tell which is better for what I do. And from what I've found in all the shopping I've done for my current equipment, the people who have used the equipment know the performance better than any spec sheet or benchmark.</p>