I’m sure there is something more sophisticated out there but I like Peas and oats that will winter kill in my climate. And then I would just plant into it, no tilling, just mulch in place. A particularly blend of this is sold by ‘Johnnys selected seeds’ but I’m sure their are others. I think the main question is how will you it, kill it, and incorporate it. What tools you have and what techniques you use may better determine the right choice.