This is want I want for my large 3D printer:

Box-like frame so that I can enclose the machine if it's not already enclosed.
Heated build platform that goes up and down instead of back and forth.
24-volt electrical system.
All-metal hothead.
Direct-feed extruder instead of Bowden-feed.
Build volume of 400mm x 400mm x 400mm or larger.
Can use all kinds of filaments.