One for the wishlist.
I like to map the PTT button on my joystick to respond to ATC (as in RL) because I dislike having to interact with the ATC panel. However, it can only be mapped to a single value so I map it to 1 to choose the first option. This is OK for most purposes whilst in flight, but not on the ground in cases where an ATIS frequency (or more than one) is available. For some reason Tune ATIS is always option 1 when present which means having to interact with the ATC panel or guess which number the option you want has been assigned to). It would make more sense for the most likely response to be mapped to No. 1 when on the ground. E.G. (for IFR)
Master on, Engine(s) off: Tune Ground/Clearance followed by request IFR clearance.
Master on, Engine(s) on: Request Taxi
Holding short of the runway: Request Takeoff clearance
Just landed and turned off the runway: Tune Ground followed by request Taxi to Parking/Gate (could be dependant on aircraft being an airliner or not)
If ATIS were always the last option on the list I think this would probably work as is now.
Another thing that bugs me is that when you switch from Com1 to Com2 and vice versa on the avionics panel this is not reflected on the ATC panel so you still have to manually change the tab there from one to the other! Every time I have to open that panel reduces the immersivity of the sim which is why I dislike it so much.