What is the best move against 4.Qxd4 in the Sicilian Dragon?

I was winning a lot of games with the Sicilian Dragon where 4.Nxd4  was played, but losing all against 4.Qxd4. What would be the best way to play against this line?

I would think Nc6 or Nf6 would be a fine move.

There's only one line where White can avoid a tempo on the queen after Nc6 and it's an exchange on c6. Black is already in a no-hurry position after six moves which is quite good in itself. After that you can fall back on developing principles and go to middlegame without any trouble:

My best tip would be to continue with Nf6, g6, Bg7 and castle. Unless they play Bg5. Then g6 is quite straightforwardly not a good move.

Thank you so much guys, I'll implement these ideas in my future games.😃

I would think (but what do I know?) that Nc6 followed by Nf6 seems pretty solid.  

These Chekhover lines are no joke.  White has a few potential plans up their sleeve. 

OP should put in a bit of time to understand these positions.

I absolutely would!! Can you suggest a good place to start?

I've played this line a bit as White. I find many opponents, following the exchange of the knight on c6, worry about the queen in the centre and can't resist attacking it with ...e5. Then the d6 pawn becomes vulnerable after White castles queenside.

I mostly play Nc6 on move 2 so I don't see the Chekhover all that much, but from what I remember white's 2 main plans are

1) Nc3 Bg5 0-0-0 Re1 White develops as quickly as possible, puts all his pieces on natural squares, places his rooks on d1 and e1 and looks to pile on the pressure.

2) White plays c4 and castles kingside. Play is a little slower with the Maroczy bind structure.

I don't know about too many resources, but a quick search online found a bunch of free videos. 

Hope this helps