Have you ever wondered what the various fillet types are used for in the fillet dialog?
The edge fillet is the default fillet and simply allows you to select an edge and enter a value for the fillet. In case you have more complex needs the other two types can often create what the edge fillet cant create. The face fillet allows you to select two faces and enter a radius. The unique thing about the face fillet is that it will fill in areas that the edge fillet cant - take a look at the image below for a few examples.
The final option is a Full Round fillet that allows you to select three faces and it will create a full round fillet even if it isnt a constant radius.
Next time you need a more advanced fillet give one of these options a test drive.