Thanos is far too powerful physically and too durable for Vader's Force abilities to overcome.
Darth Vader is a terrifying opponent within Star Wars, but Thanos operates at a completely different power tier. The Mad Titan has traded blows with the Hulk, tanked attacks from Thor's hammer, and survived encounters with cosmic entities. Vader's Force powers, while impressive, simply cannot scale to this level.
Vader's Force choke is his most viable attack, but Thanos has withstood telekinetic attacks from far more powerful beings. His Eternal/Deviant physiology gives him resistance to most forms of manipulation, and his willpower is among the strongest in Marvel. A Force choke would likely annoy Thanos rather than threaten him.
The lightsaber is effectively useless here โ Thanos's skin has withstood planet-level impacts. Even if it could cut him, Vader would need to get close to a being who can shatter continents with a punch. Thanos would end this fight with a single blow.
Vader's Force powers allow ranged attacks without physical contact, and his precognition provides tactical advantage. The Force choke targets the throat regardless of overall durability, potentially bypassing Thanos's external defenses.
Thanos has fought the Hulk hand-to-hand, survived attacks from cosmic entities, and possesses intelligence and combat skill alongside his incredible power. A single punch from Thanos would destroy Vader and his armor.
Thanos wins this overwhelmingly. The power gap between Star Wars and Marvel cosmic is simply too vast. Vader's Force abilities cannot threaten someone who has wrestled Galactus's heralds.
Darth Vader also fights
Thanos also fights