I've got a vision-only model Y. I don't know how good the radar-based ones are, but I do know the vision-based adaptive cruise isn't great. Does a fairly poor job of maintaining a consistent distance to the car ahead, compared to other cars I've driven. I also had to turn the automatic emergency braking to its minimum sensitivity setting after it slammed on the brakes a couple times for no reason.

So I don't know if the radar-based was better, but the vision-based isn't very good imo. (FWIW the vehicle's been great otherwise.)