Paramedic here. I've done most of the flashy things you can do in EMS, but my "most rewarding patient interaction" was actually something that happened when I was an EMT-B doing a routine discharge. Your mileage may vary though.
911 is a very different beast, but once you've done it for a while it's not so scary. Somebody calls, you show up, you figure out what's going on, fix the problems or at least begin addressing them, take the patient to the hospital.