Or do you just want somebody to talk to?
Even when nothing works, there will be others who will try to fix them. A radio of some sort may seem like a silly thing to keep around, but it may be what saves you. Any radio is better than no radio, but some will be more useful than others.
The first type of radio you might find is your standard AM/FM radio. You might not hear anything ever, but if there's an organized government of some sort, trying to contact any survivors, you can bet they will broadcast over those stations.
Another useful radio to have would be a short-range walkie talkie set. If you are in a group and go on a scavenging run, you could easily split up, cover twice as much ground, and still be in contact with each other. This would keep people alive.
The last type of radio you might want to have is a CB/UHF radio. While these may be dated, they are
still reliable and can help you be heard as well as help you find others.
Now all you need is a bunch of batteries.