What cars make the best candidates for EV conversions? Generally, the smaller and lighter the car is, the better. You'll get better performance, more range, and the conversion will cost less. It's a similar story to petrol vehicles, except there is a far greater economic advantage to keeping it small. It is not impossible to do heavier vehicle conversions but you will spend a lot more money to match the same performance as a lighter car. Generally look for the smallest car that will fit your needs. Aerodynamics will also play a significant role in the energy use of your EV, especially at higher speeds, so choosing a slippery car means it needs less power at a given speed and a smaller battery pack. It also makes sense to convert cars with relatively high mileage or even blown engines, since you can purchase them more cheaply, and greatly extend the useful life of the vehicle.
Here is a short list of possible donor vehicles for EV conversions ranked by weight