Wheel Size: We recommend for wheel size bigger than 14inches. Smaller tires tend to give bumpier ride.
And also, bigger wheel are able to ride over pothole on the road.
Suspension: A good to have component. It helps in cushioning your buttocks against bumpy road condition.
Brakes: Your safety should always come first, and brakes are important when picking an electric bicycle.
There are 3 main types of brakes on electric bicycle:
Drum Brake: Low maintenance but less effective at stopping you quickly.
Disc brakes: The best of all but will wear out over time. They will eventually need to be serviced, just like a car.
V-brake or C-Brakes (Also known as rim brakes): Cheapest to replace, brake shoe wears out pretty quickly.
this blog was very helpful thanks.