Roy Thomas's Ragnarok storyline, the one that introduced Red Norvell, had Sif state Thor represents about half of Asgard's military strength and Mjolnir represents about half of Thor's strength. Take away the hammer and Thor still represents about 25% of Asgard's military power. This is minus Odin.
How much then do you think Hercules represents of Olympus's military power? The two pantheons have usually been treated as about equal in power. However, the differences between them and the differences between Hercules and Thor are worth considering. This is keeping their respective skyfathers out of it.
To me, Hercules at best represents about 20% of Olympus's military power. Maybe less. This is not a knock on Hercules, but based on the differences between the two pantheons.
Thor is Asgard's greatest warrior. In strength and fighting skills the two are close enough the difference is virtually negligible. Thor makes up so much of Asgard's military power because of Mjolnir. Thor could easily summon tornadoes that would render most of the Asgardian army useless. Physically, he is of course far more powerful than any other Asgardian shown.
The other factor in regards to Asgard is the lack of powerful Asgardians. The more powerful Asgardians like Skurge, Loki, Hela, and Amora traditionally fight against Asgard. They are not part of the military unless the situation forces them to be. Njord the sea god has hardly been shown and when he has was hostile to Asgard. Tyr is handicapped. Balder is a glorified light bulb. The other named Asgardians lack the healing factories, durability, or esoteric powers of the named Olympians. They are usually only more skilled and maybe a bit more durable than the average Asgardian.
Olympus is different. Hercules is without a doubt its single strongest warrior and an important military asset. Based on what I have seen he no doubt has a better healing factor than Thor. Yet he lacks Thor's energy powers and the other Olympians have their own powers. Apollo is a walking sun compared to Balder. Artemis has magic arrows. Ares has a powerful healing factor and lacks Tyr's handicap. Neptune has been shown fighting aside Olympus in battle and he has vast powers of his own. Hermes has his speed and is no slouch in fighting so he is at least a match for Hermod. Hephaestus may not be the best fighter, but he builds some of the best war machines around. Athena is supposed to be a great fighter as well along with being a genius. Eris can mess with a person's mind. Even Hera has been shown joining in the battles.
In the end its not necessarily one pantheon is stronger than the other. Hercules represents less of Olympus's military might because the power of the pantheon is spread out more among them.