Saw this discussion online recently. Heard recommendations for avive, Phillips heart start, and Samaritan. Zoll was also mentioned. Some said figure out what local EMS was using so pads would be interchangeable. And also consider just buying whatever is cheapest.
Agree with doc above though, but it's hard to say. I don't want to insult your intelligence, but just because someone goes into cardiac arrest doesn't mean a defibrillator will revive them. There are many reasons it can occur, and several different heart rhythms. Only 2 specific rhythms will benefit from defibrillation. But making sure everyone in the home knows how to effectively do compressions can definitely be useful in all scenarios.