As the CDJ-200
has been scratched from the list this makes this easier...
You should ask yourself the question: What do I want to do with my deck ?
If you play out a lot in clubs and on event where you come across CDJ-1000s (any version) you might be better of with a CDJ-800
or a CDJ-800
MK2. As the 800 and the 1000s have simular jogwheels you better get used to the one you use the most
If you play mainly at home and want to use the deck in the digital domain the CDJ-400
would be the obvious choice. It has a platter simular to it's bigger brothers but smaller in size. But also you can use it with USB storage devices and as MIDI device to control DJ software on you laptop or computer.
New models for 800 and 1000 will not be released soon, don't worry
ps, watch my video's on the topic at these links to see all features and functions of all the decks (follow the banners)