In your opinion, what is the best bird food?

I live in the Great Lakes region (Ohio). My condo has a patio, where I have a flower garden, herb garden, my beloved grill, and a bird feeder. I buy bird food anywhere I happen to be where they sell bird food or where it is on sale. Sometimes the package will say that this particular mix of seeds will attract certain birds. I do not pay a lot of attention to that, I just keep filling the bird feeder, and the birds (and squirrels and chipmunks) keep coming and eating it. I am starting to think that maybe I should apply more science and less shopping convenience to my selection of bird food. Is there a specific seed, or mix of seeds that is inarguably the best for my part of the country?