Thanks for posting. These are the two we're considering (Sienna v Carnival).
The main thing it's coming down to is the adaptive cruise and lane keeping. I believe the Carnival EX and up look really promising here, with Highway Assist. And the 2021 Sienna looks to have lesser lane keeping capability especially, in that doesn't have the latest generation of SafetySense hardware.
But finding an EX Carnival or higher and a Sienna to drive has been impossible for us.