To me battery life and record times are the key features. I want to be able to start recording when I leave the house and just let it run. The one feature I regret not getting is a USB port to ease downloading. Even without one, downloading is possible, just time consuming through the headphone jack connected to the microphone port.
My recorder is a simple audio recorder, uses AAA batteries (which seem to last for hundreds of hours of recording), and has the capacity to record dozens of hours of audio. It also fits perfectly in one of the spare magazine holders for my Glock 9mm. I delete the recording each day when I get home--unless something has happened.