I pick Hydroman on this one.
Sure he's vulnerable to quick drying cement, electricity, and extreme heat, but using those 3 methods to defeat Hydroman is well beyond the intelligence level of Juggernaut. And that's Juggy's short coming...
Hydroman really can't do much/any damage to Juggernaut, but he can do things to gain the upperhand....like jump in the ocean or harbor, or he could just find a large body of water and use it to contain Juggernaut.
He could force water into Jugg's ear and give him a screwed up ear-ache while throwing off his equalibrium. Who knows....the only thing we know is that Hydroman can't be knocked out by using fists.