When it comes to deciding on the most ideal type of ADU, there is no set answer, and it varies per individual. To determine which is right for you, consider the structure’s purpose, you budget and resources, and preferences.
For example, if you live with your family on one lot or property and want to have your own lifestyle, a detached or conversion ADU is ideal. It can offer you the privacy you want as it is separated from the main dwelling. For the same reason, this type is also perfect if you consider having the structure as a guest house or a rented unit.
Meanwhile, if privacy is not your requirement or concern, your other options are JADU and attached ADU. JADU units are more cost-effective, as you will not have to build a new structure, which could also be a good thing for those who do not have extra space in their lot. There wills till be expenses for the conversion, but not as much as with an attached ADU house. After all, there may be a need to update the adjoing wall for fire-rated separations, resulting in added cost.