Smoke Detectors can give you a false sense of security
Ionization type or "the cheap alternative - photoelectric". So many people have fallen into the trap of just looking at the price of an item and taking the lowest priced item... not always the best as in any business quite often you get what you pay for.
For the small price difference go with the Ionization type and do yourself a favor. The photoelectric type don't always see the smoke quick enough and when they do you may find that you can't see your way out of the structure.
Ionization type smoke detectors are typically more responsive to flaming fires and therefore might very wall be a better solution for your family.
If you are an agent and notice your listing doesn't have smoke detectors, then you decide to purchase some and install them... make the right choice for your own safety.