I've used both.

Conti ultra sport rolls exceptionally for such a value tire, the best out of the two listed, but have virtually zero puncture protection. If you run them long term, they get cut up really bad from road debris. You might be able to get a pair for really cheap from a bike shop as the ultra sport is/ was one of the more common tires that came with bikes and buyers often opt to upgrade from them. They become what is called take-offs.

My vote goes toward the zaffiro, it's a more robust tire overall compared to the ultra sport and has a more durable casing and tread.