I think Khabib easily. I dont think its possible to get in that dudes head. I think there is like a 20% shot Conor can throw a freak knockout punch but its a longshot this time since Khabib is so disciplined.
ISIS is a bit more brutal in close quarter combat however the IRA has a much better long game and can really toss some bombs so... I've gotta go with the IRA on this one.