According to the Virginia Cooperative Extension, black-oil sunflower seeds are the most universally liked. Goldfinches, blue jays, cardinals, chickadees, grosbeaks, doves, purple finches and more flock to feeders offering black-oil sunflower seeds. Be sure to spread some on the ground, too. Doves and juncos prefer to eat on the ground instead of from feeders.
Other types of sunflower seeds, like striped hull, shelled or hearts, are also excellent choices and will attract plenty of birds.
White millet is a favorite of finches, sparrows and juncos. A tube-style feeder filled with white millet attracts plenty of finches that will be happy to spend the day eating seed.