The list is LONG but to touch upon a few...
3 axis autopilot would be number one towards making it a pilots airplane
A true pilot's airplane wouldn't have an autopilot
An FMS that actually talks to its counterpart without needing a crossfill
There is an update for this, costs $$$ though
http://www.q400.com/q400/img/video/e...agation_en.mov
Not needing to press alt sel everytime you change altitudes
Yeah, they kind of F@#%ed that one up huh?
Make the gear about 3 inches taller so we arent limited to 7.5 degrees before we strike the tail
See above comment... and they want to make a stretched version?!
*** are they thinking?!
A more accurate autopilot that can intercept a loc from a standard 30 degree intercept 10 miles out at 200 knots without flying through it and then S turning
Oh hell yes
Build the fastest part 121 turboprop in the world that cant do 250 knots below 8000 feet due to certification when the plane could easily do 300+ (illegally) but still...250 would be nice without the redline in the way.
Well, if they are going to do that then it would be nice to be able to use the spoilers in flight.
Regardless it is weird having an airplane that can do 282kias at 10,000 but only 245kias at 8,000.
A more bulletproof autopilot that does not kick off in light to moderate turb
How about a better autopilot. PERIOD!
Figure out a way to put a more forgiving gear on it..ive been flying it for well over a thousand hours now and a good landing is a guessing game for me and anyone ive seen fly it...there is no fool proof 100 percent trick.
Good Luck, and if you find one let me know!
For things that cant be changed for the common type rating...
Lose the condition levers...they are just buttons anyway with a few "settings" that could easily be replaced with buttons that are already in the plane.
Condition Levers = Closest thing to flight spoilers this airplane has.
FMS, Fadec, Glass....caution warning panel ?!....lose that stupid thing and put an EICAS in it.
Hey! Something in common with Boeing!
minor annoyance....lose the bus tie switch that isnt actually connected to anything
Then the old dash pilots will go insane looking for it! 
While you are at it...put the wings under the fuselage because high wings are for primary trainers and look stupid.
Makes it look bigger, but we're not compensating. Are we?
Has been helpful avoiding the construction in DEN, although the rampers really should still be paying attention when they guide us in even though our wings pass over all the orange markers.
And last but not least......pay me more to fly it
Amen