important add on
Good advice and comments so far. I would add that all things considered, one of the more important considerations is being able to hear the radio clearly. Having headset adapter plugs is important. If your primary radios go down, you will have to get home and land. If it is a tower controlled field, you will annoy them less if you are not shouting and asking say again.
The built in antenna is perfectly adequate, though some wire for external. In these scenarios, you will likely be facing right at the tower, with a line of sight from the rubber duck antenna. I learned to fly before headsets. Shouting and tilting your head towards a speaker were a terrible classroom environment. The technology we have today is a bit better. BTW I also carry the ILS capable unit mentioned in other replies.