I would prefer Theo Hernandez or Alex Telles. But Theo is happy in Milan, Telles goes to MU. Then there is Jose Gaya - very inconsistent performer. Alejandro Grimaldo another name - probably affordable and had 20 assists last 2 seasons, but in Portugal. There is also this dude Raphael Guerreiro - it will be his 5th season in Dortmund, maybe time to move on but doubt he's good enough.
So Gosens it is then.