Personally I'd like proper light controls and light shields so that the other chap doesn't get blinded by their colleague when they need light to perform something. I'd like window wipers that work and controls that have appropriate power/feel ratios. I'd like an FMS that has a consistent control and simple 'buttonology.' I'd like footrests that don't dig in just below your kneecaps when you have the proper seating position. I'd also like an autopilot interface that makes it easy for you to fly the aircraft rather than the other way round. I'd also like indicator lights above the mode selector buttons on the glareshield.
I fly an Embraer "E Jet" and this aircraft, whilst very capable, is a complete and utter pain to fly if you compare it with a Fokker (70/100). In the list above, the only thing Embraer have done a reasonable job on is the windshield wipers. But if I had to list it's good points (from a pilot's perspective) I'd include the FADEC engine controls, steering, brakes and external visibility (except with with Flaps 5) and the overhead panel which contains no useful information whatsoever, so can be completely ignored. But I don't think these make up for the diabolical rubbish supplied by Honeywell which we have to do battle with each day.
PM