The biggest loser from the appearance of Isis was Turkey.
The Americans won from Isis, it allowed them to justify their kurdistan agenda.
Russia won from Isis, divided the opposition and promoted Russians as the good guys, despite murdering far more then Isis in Syria.
Iran won from Isis, nearly every iranian shia were joining the world in insulting Muslims. Its what they do best.
Assad won from Isis
PKK/YPG won
Turkey lost since the opposition was not only massively divided but was entirely delegitimised with fanatical islamist jihadis cutting heads off, throwing gays off buildings, cutting people up and placing their body parts on metal fences. I remember watching one video where a kid was collecting heads in a duffle bag. The stuff that was coming out of the so called "Islamic State" eclipses anything ive seen in any horror movies.
That underlying ideology btw comes out of saudi arabia and is internationally promoted and financed by the gulf states. Many muslims today in the west with out realising it have been indoctrinated in the same filth, that was originally used by the British to divide Muslims against each other. So all Muslims need to be aware of where they are getting their islam from? Is your mosque saudi financed and your imams saudi trained, if so stay away. Your being indoctrinated in an ideology that is designed to destroy Islam from within.
The Syrian people themselves lost, since they were subject to the terror and their cause effectively ended.
The biggest loser though was the religion of Islam itself and her followers. Isis was really the catalyst in creating an international perception that all "Muslims" and all "Muslim" majority states were evil and must openly be opposed. Today speaking out against Islam and anyone or anything associated with it is praised.