I think Loki's magic would give him the win and make the most of that barbarian horde. When it comes to physical stats Sorbo Hercules has movies and a series to flush out and push his limits but I think Loki has the strength and endurance to match him. His skill being more relevant here as he was able to hold his own in his physical fights and could take herc's straight forward style.
Based on average showings, Herc doesn't outclass Loki by much. Herc has had trouble dealing with peak humans like Xena and Eriks the Boxer. He steps it up some against gods like Ares and Apollo, but he's never punched anyone out of the atmosphere. He may knock them back a few hundred feet, but that's about it.