He's asking about the mountain bike style SPDs. I recommend PD-M520 pedals. Cheap enough and super durable. I have a set on my mountain bike and they have endured repeated bashings on rocks, dunking in water, and riding in mud. I did use them on the road for a couple years as well.

Whatever the listed degree of float is you can add a bit to that because the cleat will travel a bit into the spring before it releases.
Shimano PD-M520 SPD Bike Pedals | Jenson USA