Individual landlords would not be a priority for me, I would start by prohibiting LLCs from owning residential property, convert existing apartment complexes into residential co-ops/condos, and force existing corporate landlords to sell their properties to individual buyers at a cost determined by the state.

For individual landlords, I'd just prohibit them from acquiring new properties they don't live in themselves, and make it illegal to transfer ownership of a rental property to anyone else unless they intend to live in it (eg via inheritance, sale, etc.).