The best?

Circa early 1970's...Hamilton Sundstrand full authority RNAV/VNAV/engine thrust management FMS, fitted to...the Lockheed TriStar.
Without a doubt.

Missing Avionics
 

Well, there is the bit of avionics kit we have (inexplicably) NOT got yet.

It is the sort of GPS moving map display, for taxiing, that I have when driving a car. With the aircraft position shown on the airport taxi chart. Why don't we have them? (or is it just me that doesn't?) It seems it would be really easy to implement, the whole thing could probably be done in software, for many modern aircraft.

It would surely reduce taxiing stuff-ups and runway incursions, particularly in poor visibility. And would compensate for all those airports where taxiway signage is piss poor. And would also help you find where parking stand Z-497 was located on an unfamiliar airport.

Yup, that is sorely missing for most. Small GA jets do have that as standard, but our big ones do not. However with the increasing number of class 2 or better EFBs around it becomes available through the EFB side of things. Which has the charm of an easy retrofit even to older aircraft.

Track diamond / indication on ND.

We are talking an RJ!

Best inventions in order have to be:

* AoA indicator or Flight Path Vector (amazingly useful)
* Track indicator
* Tie: EFIS/GPS/EGPWS/TAWS

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