I am very much disappointed with super73 s2. You can check my display. Also motor seems to have issue as it make noise. Super73 told that they will send me a replacement motor but I have been waiting for it over 3 months. I dunno much about Ariel Rider but be careful with Super73. Their e-bikes are cool but not well built.
My lock on S73 S2 fork was missing when I received the bike which I didn't make a big deal and wait for the part to arrive. But what annoyed me was my motor not working after one month. Unfortunately lots of people are facing same issue with Super73 motors. It is better to stay away from Super73 until they figure out the motor issue. They said V2 motors won't have this issue and now saying same thing for V3 motors.
Ariel Rider is definitely a better e-bike with better specs except battery. But it costs almost half of super73 and they don't have many quality issues. Also I see their owner forums, this year they seem to improve their customer service. But in the end it depends on you, what kind of an e-bike you like and prefer.
Super73 offers you to be a part of a social club but has lots of quality issues.
Ariel Rider don't offer you that social thing but you get a high quality e-bike.
Speed of Ariel Rider is definitely solid, I get up to 34mph regularly, and its zippy enough that I can keep up with cars on side streets and in traffic. Generally speaking, if there's heavy traffic, I get to where I want to be way faster than in a car, as I can split lanes and jump on the sidewalk whenever I want. I changed my crank to a larger one and on pedal assist I can reach 38 mph on my X-Class.