I have 3 feeders I fill. Two get black oil sunflower seeds and sunflower hearts. The third gets some mix I bought to cheap out. The cheap mix has Milo, Stripped Sunflower seeds and some other filler. I have to fill the two with sunflower hearts every four days. I have seen as many as 13 Gold Finches on the sunflower feeder. In two weeks, I have only seen two birds on the cheap seed feeder and it is still basically filled to the top. Another week or two and I guess I will have to dump it.
I have said this before, the Cardinals, Finches, Woodpeckers and Blue Jays love the hearts. If you want these birds, hearts are the way to go. The cheapest sunflower hearts I have found are 40 lb bags for $50.
The Ontario bird feeder cam is back online for the winter. When things get cold the arboreal birds they attract are really colorful.
https://www.allaboutbirds.org/cams/ontario-feederwatch/