Our most productive plant is K. laetivirens, an unusual succulent that yields many plantlets around the edges of its leaves. There are varieties: ours is bright green, resilient, and likes small pots.
We grew a large one (to truly become a mother of thousands). We cultivate its many plantlets in glass pots and anonymously leave them for others in our neighbourhood in Toronto.
Keep in mind these can be invasive and they spread incredibly easily. Some people might not appreciate having to deal with these.