Coverage
Shaka is strongest on Hawaii. Road to Hana is the tour people name first, and they sell full-island bundles for Maui, Oahu, Kauai, and the Big Island. They also cover Yellowstone, Utah parks, Yosemite, the Pacific Coast Highway, and other scenic drives, plus a few walking tours. Off those bought routes there is nothing to play.
Passenger Seat has no catalog of routes. Live watches where you are and narrates the landmarks and towns you pass. That holds up on a Tuesday commute and on the drive to the park, not only on the loop they sold.
Buy Shaka when the destination is in their list, especially a Hawaii drive. Use Passenger Seat when you are on a road they never sold.

