Sure but how big an impact did Khedira have for Real Madrid when they won the CL in 2014? Not really a big one, the same for Germany during the World Cup he was not one of the most vital players and didnt even play the final against Argentina. He started for Real Madrid in the 2014 final, but was taken out after 59 min and wasnt on the field when they turned it around.
Vidal havent won a CL or a World Cup, and nothing is given that he ever will. His impact for Chile and Juventus and now Bayern Munich is way bigger than Khediras for RM, Germany and now Juventus - i will hold on to that.
Khedira wasnt the reason Germany won the World cup, also not the reason Real Madrid won the CL. He is not really that important for his teams the same way as Vidal.
I'm not even debating that Vidal is the better player, but that doesn't mean one has to belittle Khedira all the time.
They aren't even the same type of player. Vidal is a beast, and best as back to back mid, Khedira has always been best as holding mid, no fancy shit. The quiet worker who frees up teammates by staying back and quick passing the ball forward.
In this role, as pure holding mid in a 4231 with enough attacking players surrounding him, i prefer Khedira over Vidal, simply because he is way more intelligent than the hothead Vidal and more unilkely to give away stupid fouls or misplacing a pass. Not to mention Vidal as holding mid is a waste and takes away his biggest strenghts.
Vidals impact for us in he CL final against Barca was enormous btw.