Having the following is a must for me:
No excessive lighting (This is why I'm getting rid of my BlackWidow),
Mechanical switches (preferably Cherry MX blues),
Being able to use custom keycaps,
and most of all it has to be relatively 'simple' (No extra buttons and so on.)
Now, I've looked at a couple of keyboards so far:
Noppoo mini,
Happy hacking keyboard,
Steelseries 6GV2
And the Zowie celeritas.
Any ideas?