Step Lip. I think on a older car the smooth lip is to modern and takes away from the car. But again its that individuals car so they must make the choice that they like.
If you don't love to clean your wheels don't buy a set of fat lip wheels. The reverse lip creates a channel between the step and back of the spokes. That channel will trap water whether you are driving in rain or just washing your car. On the way to RTTH's last year we got caught in the rain. We stopped for gas over 20 miles after it had stopped raining. Both rear wheels were still full of water. That water becomes really nasty with all the brake dust and road grime and it REALLY makes it tough to get the wheels clean again.
I switched to a set of step lip Forgeline and don't miss my fat lips at all.