Vista Cruise without a doubt. I found the throttle rocker unsafe in parking lots. If I hadn't gotten on the clutch fast I'd have run into cars, buildings, anything in the way. Just a slight movement of your right hand produced a big movement on the throttle.... generally when you wanted it the least.
Throttle rockers are great on the road but you have to survive the parking lot to get to the road.
The Vista Cruise has no vices that I can see. It allows me to let go of the throttle for extended periods pretty much whenever I want. You just need to keep an eye on your speed because the balance point for a flat section isn't going to be the same as on a hill and your speed can vary.