It'd be great to have a very precise final output -> a SLA/DLP type techno (SLS seems not exactly home friendly to me).

I'm definitely in favor of a 25liter+ print volume.

A mature software and hassle free process (no tinkering with cleaning products and bed taping).

A smart interface/slicer : pause, material quantity check, failure recovery, ...

And, while we're at it, why not the integration of very innovative open source programs on the web like the fantastic Make it stand !
http://igl.ethz.ch/projects/make-it-stand/