Adding to the list, I would also prefer getting a new voice codec so the radio qualities can be improved. Voice now depends on the quality of the microphones pilots and ATC are using, and only few have good ones.
Secondly, I would prefer enabling voice on UNICOM. I feel that typing while flying is hard to do, multitask wise, especially in GA planes VFR. Voicing your intentions, I feel, is better than typing your intentions.
Finally, I would raise the standards of pilots and their basic standards of connecting and what to do on the network. Here is an example. During an event, I saw o