What an excellent topic!
Starting with fave first...

Tyros,
I am so glad I (eventually) took the plunge and bought the Ty. It really is my dream keyboard at the moment. I would prefer it to have a digital out and more modern storage facilities (like they put on the 3k) but apart from that I have not one complaint!

9000PRO,
I kept this board longer than any other board I ever owned. I loved the keyfeel and the four sub outs. Playing it was wonderful and I half wish I had kept it alongside the Ty (but that would have been greedy!)

KN6500,
Enjoyed this board but it was to be my last technics board after years of technics ownership. (unless you count the KN7000 fiasco.... see below!)

KN6000,
I thought this was massive jump from the KN5000 at the time. I remember the sound system blowing me away in the shop and I just had to have it!!! Kept this board until the 6500 (above) came out and upgraded just for the sake of it really. Not a lot of difference between the two boards.

Technics KN5000,
One of my first 'real' boards. I felt like a million dollars when I bought this board. I had never spent as much on an instrument before and I adored it. Played one recently and was surprised how much I felt it had 'aged'.

Roland EM 2000,
stunning sound but I could not settle to it. I loved some of the styles, especially the accoustic piano stuff, but the menu system and OS in general was imho abysmal. I could not get used to it at all. Only kept the board about six months. Bought this after the KN5000 but went back to technics with the 6k after it went.

Korg i40m,
Like Scott says modules are just not practical. Trying to get at the buttons when playing was nightmare. I loved the VH feature on it though. Very simple to use. I hated the OS and the way of loading styles with a vengance. Even the roland was childsplay compared to Korgs way of doing things! It is the one thing that puts me off auditioning the PAx.

Technics KN3000
Down at the bottom because it is so old now. I quite liked it at the time though.

Technics KN1500
ditto

I am not counting the casio's and 'toy' yammies I kept buying when arranger technology was in it's infancy (and for that matter so was I )

Best wishes
Tony