Juggernaut was never said to get stronger, what he did to Thor in the Eighth day storyline was show how much more durable he was than Thor, Marvel officially stated that Thor could outlift Juggernaut; for example a diamond is harder than steel, but steel can shatter a diamond (body armor factor). The Hulk is stated to be quite a bit weaker than Juggernaut in a calm state, but when he gets excited, and his andrenaline starts flowing he can exceed Cain in strength.
Strength Level: The Hulk possesses superhuman strength of the Class 100 level, enabling him to lift (press) in excess of 100 tons. The Hulk only attains this strength level when he is enraged. In a totally, calm state his functional strength is significantly less, perhaps in the 70 ton range.
Known superhuman powers: The Hulk possesses the capacity for "nearly limitless" physical strength. In times of stress the Hulk's adrenaline level escalates, causing a corresponding escalation in strength. "This is not accompanied by an additional gain in mass", but does appear to promote increased levels of energy efficiency. "To date the Hulk has never apparently been provoked into demonstrating a maximum output of strength"; hence, its upper limit remains a mystery
I would launch an argument for the rest of the contenders, but it is clear who can lift more, as far as Marvel is concerned. If Juggernaut was considered to be strongest why didn't they use him to go toe to toe with Onslaught? the fact being is that without his forcefield Juggernaut was placed somewhere in the region of Simon Williams in strength, who is weaker than many of the characters in the list above, Thor was seen not only outmuscling Cain but he beat the tar out of him when he magically negated his forcefield. And the Hulk has outdone Thor one on one in issue #440 and I must add that he was fighting a warrior madness Thor. Yet he was still tossing him around.