I've driven a few electric motorbikes and I've always been impressed. The torque from an electric motor really works well on an electric motorbike, giving plenty of zip when you need it.
The best ones I've actually ridden are the Lexola electric scooters, which are distributed by Urban Mover (
www.urbanmover.com).
They're pretty nippy, built well and have a decent range. All but the bottom of the range one has silicone gell batteries and can be fast-charged in around one hour.
Prices start at £895 for their basic moped and go up from there.