Well, given the situation there at least since 1919, which turned everything upside down, we should stay out of there.
Didn’t approve of going in, and I think our funding and arming of “the good” (/s) al Qaeda, was the spark that exploded ISIS on the scene.
Once you’ve gone in, you have people who have telegraphed their support for you. When you just turn around and walk out, it leaves them hanging, and others out there who may be willing to help you in the future, realizing that wouldn’t be a good idea.
My efforts right now would be working with the Assad government and the rebels (whoever they actually were/are) to negotiate a settlement where each side could live with the situation in peace.
I don’t believe this civil war is helping anyone, and even if the rebels won, we don’t know for sure that another Islamic caliphate wouldn’t follow on there.