After being imbued with the destructive power of the demon-god Cyttorak, the Juggernaut became one of the strongest forces in the Marvel Universe and has shown that he is even stronger than the Marvel Cinematic Universe version of Thanos. Cain Marko usually tangles with the X-Men as his stepbrother, Professor X, is their leader and the Juggernaut has an unending hate for Charles. On occasion, however, the Juggernaut does battle with forces outside of his realm of existence, and during one of those battles he proved that he is stronger than Thanos.
In X-Men Black: Juggernaut by Robbie Thompson and Shawn Crystal, Cain Marko is being put to the test by Cyttorak himself to see if he is still worthy to carry the mantle of the Unstoppable Juggernaut. During this test, Cyttorak and the Juggernaut fight one-on-one in a brutal test of Marko’s strength and ferocity. In the end, Juggernaut wins in the fight against Cyttorak and is rewarded with the demon-god’s permission to continue holding the title.
The Juggernaut’s victory over Cyttorak is something that Thanos cannot relate to as he was neutralized by a spell that pulled a mere fraction of Cyttorak’s power. In the Marvel Cinematic Universe film Avengers: Infinity War, Doctor Strange is battling Thanos on the planet Titan and is using every spell in his arsenal to defeat the villain and remove the Infinity Gauntlet from his hand. One of the spells Doctor Strange uses is the Crimson Bands of Cyttorak which bound Thanos to the ground and made him unable to rip free. Being essentially neutralized by a spell that only uses a fraction of Cyttorak’s true power would not bode well for Thanos if he were to go up against Cyttorak as the Juggernaut did.
The Juggernaut defeated Cyttorak while the MCU version of Thanos lost to a spell using Cyttorak’s power, so not only would the film version of Thanos easily lose to Cyttorak, he would also be defeated by the Juggernaut. The Juggernaut is a living, breathing extension of Cyttorak in the real world, so if Thanos couldn’t break free of the Crimson Bands of Cyttorak, he would have no hope in defeating essentially a version of that spell that can demolish rather than simply bind.
Since this comparison is exploring the strength discrepancies between the comics Juggernaut and the MCU Thanos rather than the comics Thanos, the original version may have a chance against the Juggernaut. However, with the evidence given in the MCU of Thanos’ power level in relation to the Juggernaut’s most impressive victory, Juggernaut proves he is stronger than Thanos.