Seeing as Goku is literally at the level of Gods I think he would win. Even if we say a lightsaber could harm goku, which to be honest it probably would, Goku is one of the fastest beings in the universe and instant transmission being [i][b][u]Instant[/u][/b][/i] Vader wouldn't land a blow. If we go even farther and say that Goku used Ultra Instinct, he would literally be untouchable. Im not big on Starwars so if anyone wants to let me know if Vader has some amazing power too so I can correct myself it would be great.