Boots to put on the ground that is. Other than Americans, we have the Iraqi Army, the Kurdish Peshmerga, and some shadowy Syrian rebels. Our Prez doesn't want to use Americans for political reasons. The Iraqis haven't fought well since Saddam Hussein's early days. They put up a good fight during the Iran-Iraq war on the 1980's. That war lasted 8 or 10 years. The Iranians had a larger population, a lot of good US equipment left over from the Shah's regime, and a scary level of fanaticism on all levels, from Ayatollah Khomeini right down to the teen age Iranian soldiers who conducted human wave attacks on Iraqi positions. But when faced with the Americans in 1990 and 2003 they crumped. Iraqi units didn't fight much, or very hard, and a lot of 'em just deserted under fire. After a good ten years of rebuilding under American guidance, they aren't even as good they were in 1990. ISIS was able to brush them aside with ease.
The Kurdish Peshmerga fighters have a decent rep. They fight hard and they don't run. Trouble is, there aren't all that many of them, and they lack heavy weapons, mortars, artillery, tanks, armored personnel carriers, even trucks and jeeps. We could help out there, but the Baghdad government thinks that Kurdistan is still a province of a greater Iraq, and refuses to give the Kurds any weapons, lest they use them to declare independence from Baghdad. And Baghdad gets huffy with us when we suggest shipping arms direct into Kurdistan.
Then we have the Syrian rebels. They have little to no rep. They have been fighting for years to drive out Assad with little success. They have been able to stay alive, and prevent Assad from offing them all, but that ain't much.
And then there are the Iranians. Lots of 'em, close by, and they have a pretty good rep. Trouble is, they are bad guys, trying to go nuclear and nobody wants that. Iran is Shia, and Iraq is split Sunni Shia. All the Sunni Iraqis would rather die than allow Shia Iranian soldiers into Iraq.
Bottom line. There ain't no good boots to put on the ground in Iraq. (except ours of course).