Any of the sunflower species grown for oil are the best. The hull is thinner than the other types and it has more meat in the seed. The higher oil content makes it more nutritious to wildlife.
I plant Black Perekovic (or something like it) which I buy from the local feed store. I've had plenty of sunflowers come up under the bird feeders but I don't know how viable the seed used for bird feeding is overall. The bulk from the farm store is cheaper anyway and I would use it for feed if it was available year round.
