So I photoshopped this since my scanner didn't work, Here's my entry:
A controller with the ergonomics of an Xbox 360 Controller/WiiU Pro Controller, Nintendo-style analog sticks, D-Pad, and Bumpers.
GC style Analog Triggers (with the Xbox One's vibrating feedback).
Stylus-Compatible Touchscreen in the middle of the controller, not too big and not too small (about the size of the 3DS' top screen). Can be turned off (unless the game requires it).
Interchangeable sticks/buttons/D-Pad, which allow for maximum customization (i.e. you can have the 2 sticks at the bottom (PS-style), like they are now (GC/Xbox style) or at the top (WiiU style).
Lengthy battery (like the WiiU Pro Controller).
Ability to play small games on its own (i.e. GB/A games on the small screen).