Having both now, I would say like everyone else - Depends on the terrain.
But overall, rear motor for comfort - The motor pushes you , its a nice feeling and quickly reaching 20mph is no sweat at all. Hill strategy - Don't slow down - That is keep your cadence up you will be fine except the...
Got a Cannondale lefty Neo at 2.5k - Used 500miles . Rides across multiple surfaces. Rides like a dream.
https://www.cannondale.com/en-us/bikes/electric/e-road/topstone-neo/topstone-neo-carbon-lefty-3-c62371m
Headaches - Cannondale lefty fork regular maintenance plus proprietary 650B wheels.
Vs...