Leafspy is the most common one recommended for the Leaf. If you are looking for a commercial one that can handle a wide range of vehicle, then there are many but price start around $500 and go way up. Leafspy is around $20 and the ELM link another $20-30
The same ELM module that you use for Leafspy will work with Torque, which is made for ICE cars. My ELM came with a Torque disk, but you can download it just like you do Leafspy. So it can handle a wide range of vehicles.
