What about Ankara´s al-Qaeda forces? Do you think the people in Afrin are better off with them?
Again, not my circus, not my monkeys. We need to stop sticking our dicks in the hornet's nest and trying to figure out who the "nice" hornets are.
The US has supported all war parties in Syria except for the only legitimate, the government. The other forces are made up and or terrorist. When for example Kurdish forces could have a legitimate status, their remote control from abroad by either Turkish-Kurdish organizations or the US-government puts their general status in question. If the Kurdish forces were solely focused on protecting their land in Syria from terrorist threats like "rebels" or ISIS and even separation from Syria within reason but not involved in land grabbing and harming the government on behalf of powers abroad, then we could talk of the a force that could gain international legitimacy. Part of the YPG forces are legitimate, part not, so in general not.