Radrover will be around $1700 delivered, and Sondors $700 delivered. Upgrade it with an LCD display and larger battery and you're still under $1000. 4 levels of pedal assist. With the Sondors you may want to have an LBS go thru it and check all the bearings, etc.. Don't know about Radrovers out of the box.
Then it comes down to style and your style.. Sondors is a much more attractive package, if you like that sort of look.. With 9000 units sold you're part of a clan!
If you're the type of person who likes to tinker and upgrade your bikes, the Sondors has a very active aftermarket, with multiple third party vendors.
For instance instead of upgrading your battery, you can buy the bike and then buy a huge 50v, 1kW battery aftermarket specifically designed for the Sondors, for $600. Increases voltage and power by 20% and is 3x the energy of the orginal battery, all without changing the look. There are many buyers for the old battery, since there are so many out there. So your net cost will be $400. Throw in an LCD and youre in for $1200 with a 1kW battery.
However, if both bikes look the same to you, and you just want to ride the bike and not upgrade the components, the Radrover will do just fine.