The idea that "Kurds"[0] are somehow more motivated or more trustworthy is literally just racist State-sponsored propaganda that has been used and abused by all sides, including from other Kurds, for various reasons over the last 150 years.
Rather than picking and choosing arbitrary, loosely aligned militias to control regions, the US needs to take a more holistic view towards the region and stop participating in the Saudi-Iranian proxy war if it wants to resolve the situation.
[0] I'm putting the word in quotation marks because they are a group of 40 million people with differing religions, alliances, identities, political views and geographical locations around the world