I don’t like adding a third option to find games. Because it will split the searching players even more.
But if you want to add it at least make it possible so that you can search unranked and ranked quick search at the same time.
For example, you can mark for it to search ranked games only. Or mark to only search for unranked games. But also add the option to mark both and so the game can be ranked or unranked depending on where you find a game first.