Yes, the Keenz! We loved it and were grateful we’d rented it. We were in the parks for long days (we figured we walked about 45 miles over the six days), and there is no way our 6.5 yo would have made it. He often curled up after fireworks (or whatever nighttime show) and slept all the way to the car. It comes with a cooler, which was awesome for our lunches and snacks. There were four more of us (DH, me, 20 yo DS, and 15 yo DD), and it was also awesome for storing any layers we shed, and souvenirs bought, etc.
We drove, so we didn’t have any experience on buses, but it is really easy to fold up. The only thing is that the wagon part has to be emptied to fold, which can be a little difficult. We folded it if the monorail was crowded, but didn’t on the ferry.
I absolutely recommend it. I worried that it was overkill, but I didn’t regret getting it for a minute.