Well, let me start off by saying I just had the basics of equipment when I started. I started with a D3000 then progressed to a D90 then a D7000 and finally a D800. As I journeyed down the path of a photographer I always upgraded when I saw the need. Never spend anything extra if you don't take advantage out of it. Specially if this is a hobby or if your body is resting in the cupboard for a long time.
Loads of people have asked me why I chose a D800 from a D610 or any other body. First off I got a good offer from cameralk for this and it was amazing. I had used a D800 and a D600 before my purchase and I felt that the D800 was the body for me. The D600 for some reason, the AF area is too small! Every time I wanted to focus on something it was always outside of the focus area :/ (considering composition). The only disadvantage about this is that the RAW file size is HUGE! around 40-60mb sometimes 70.
Nikkor AF-S 24-70mm f/2.8G ED
This is the bread and butter lens I use 95% of the time (for now :p). I have no idea not to go without this lens. When I switched from my Nikkor AF-S DX 18-200mm f/3.5 5.6G to this beast I almost cut myself with it's sharpness. @ 2.8 the DOF and the details are so amazingly breath taking.
AF-Nikkor 80-200 f/2.8 ED AF
This was the first FX lens I ever invested in. This is I think a third hand lens. Yes you heard me right, I brought this off Second Option - Buy / Sell Pre Used Cameras and Equipment and I never regretted it. It was just amazing. This is a very old lens which uses the push-pull method of zooming. Disadvantage is that focus is very slow and sometimes it never focuses in low light. I use this for my outdoor shoots with plenty of light. After I got the Nikkor AF-S 85mm f/1.8G I rarely use this now. :P
Nikkor AF-S 85mm f/1.8G
Hah the Nikkor AF-S 85mm f/1.8G. This is my portrait lens at any given time of the day. The zoom is not too much like a 100mm and the shallow DOF is just amazing. Normally this will be used like @ f1.8 99% of the time and 1% @ f2.8 or higher. Why would I invest in a lens and not use it @ f1.8? I know sometimes they are a bit blurry but that's why I take multiple shots. The bokeh is just fabulous. I love this lens.
Sigma 170-500mm f/5-6.3 APO RF
This lens is used for wildlife and birding. However I would not recommend this lens for either as the aperture is not constant and @ 500 the image tends to get softer. Also this has a considerable amount of ghosting and chromatic aberration. There is lens flare so direct light into the lens will give you really poor images.
So wonder why I got this? well 1 thing is for the reach and the other is that if used correctly this can be handled with minimal errors. Last but not least I got it for a bargained price.