D70 (The reason I went down the Nikon route, it felt perfect in the hand compared to the Canon 350D )
D200 (It felt more professional and improved in every way over the D70)
D300 (Again, huge improvement over the D200)
D300S (The only reason I got the D300S was because the D300 got stolen with a load of other gear. Great camera though, and probably my favourite camera ever, but I couldn't have justified the upgrade if it wasn't for the burglary. Silver linings eh! )
D500 (Was seriously thinking of getting a 7DII as the D300S was starting to lag behind in high ISO performance and resolution. Thankfully the D500 came out of the blue just in time and is the best crop sensor DSLR imho )
Not sure that Nikon, or anyone else, can tempt me replace the D500.
D610 and IR converted D70. TBH although the image quality from the Fx (Sony) sensor is great, neither camera have impressed with build quality or design, and after 3 years of amateur use (probably 20,000 shots) the body of the D610 now creaks when I hold the grip.
Still have all. The D750's are regularly used, The D7200 when I want additional reach with the 70-300, or with the 10-24 until I can cost justify a 16-35 F4. The D7100 with 16-85 often rides with me in the car when I'm not carrying my usual kit, just incase I come across something interesting.
I rarely buy a camera (I keep them for years). Of course I'm a consumer, but it seems that the consumerist culture has swallowed the world. It seems strange that some of us can dither about what to buy next, whilst others might be starving / living in a war zone.
In the last school I taught at I was conscripted to coordinate (make) the yearbook. I stipulated that I needed a camera then and got the school to buy a D40x. I was essentially the only one to use it so I'll count that.
D80 (gave to daughter so I could get a...)
D300 (sold this to get a...)
D7000 (wife wanted this one when I got the following two...)