Thanos wins, he has way over 100 Class strength and has similar powers to Juggernauts invulnerability, not to mention countless of other powers. So after many hours of them punching each other to no effect, Thanos could theoretically use his manipulation of the power cosmic to mess with Juggernauts resilience.
Thanos abilities:
Thanos possesses nearly incalculable superhuman power. The most powerful of the Titanian Eternals, Thanos is an Eternal mutant whose massive thick-hided body grants him the ability to synthesize cosmic energy for his personal use. (This is a trait that Thanos shares with his father, Alars, and the Earth-born Eternals, but not with most Titan-born Eternals.) Through bionic amplification, Thanos increased his physical strength and resilience to levels possibly rivalling or surpassing even the strongest of the Earth Eternals (i.e. Gilgamesh, now deceased). This indicates that Thanos' strength far exceeds the Class 100 range, meaning he easily surpasses the strength level of top tier heroes such as Thor, Hulk, Hercules, Gladiator or the Silver Surfer. Through meditation, certain mystical techniques, and the aid of the incarnation of Death itself, Thanos has augmented his power in still other ways- enabling him to tap, transform, and direct vast quantities of cosmic energy for destructive force. Thanos also possesses to ability to manipulate matter to a frightening degree as well as teleport himself vast distances, a trait he shares with many of the Earth's more powerful Eternals (Sersi and Ikaris). Thanos has also demonstrated psionic abilities (e.g. telepathy, astral projection); the limits of which remain unknown. Another remarkable trait Thanos possesses is a nearly indesctructable level of invulnerability, allowing him to take almost any sort of damage without being harmed and be almost completely resistant to reality manipulation and matter transmutation. Perphaps deadliest of all of Thanos's attributes however is his mind; his superhuman intellect and legendary cunning are totally dedicated to the annihilation of life- and the mastery of any technology or mysticism that will alow him to achieve these dark goals.
Tyrant vs. ThanosAside from his great power, Thanos is a superb tactician and is well-versed in many areas of arcane lore. He also possesses technology that allows him to teleport great distances, time-travel, and travel through alternate dimensions. Thanos is also a highly formidable hand-to-hand combatant, having fought the likes of the Galactus-Spawned Tyrant to a stand-still, with the help of a power bauble containing Morg's stolen energy, and trained his adopted daughter Gamora to become the universe's most feared female assassin. As powerful as he is, Thanos seeks to avoid physical confrontations and prefers outwitting his opponents and working through agents and thralls. Thanos is, and will always remain, a threat to all life and one of the most dangerous beings in the universe.