If by "peak" you mean Blonsky at his original strength levels, he'd win all of the fights unless Herc BFR's him; he was at least double Herc's strength with the durability to match.
If we are talking Blonsky's standard levels, then it is more interesting. A pure slug-fest I'd give the edge to Blonsky - at his "peak" standard-level showings (not including Chaos War as he was externally amped) he is explicitly more durable than the savage Hulk and comprehensively stronger than Hulk even in "you hurt Betty" mode.
Every other type of fight favours Herc by varying degrees due to the massive skill and heart edges (as well as being close enough physically).
Cheers.