Hi Negi,
I think that you overlooked the most challeging option in the 4...Bb4+ variation which is Nbd2. I have looked at the existing theory and I haven't liked it at all.
Instead 4...exd4 5...Nc6 6...Be6 can be caotic but gives counterplay to Black if White plays 7. Bxe6. 7.Bb5 allows White to pressurize by sacryficing temporarly a pawn but the resulting endgame seems holdable.

I think 3. e4 e5 is best for Black.

Here is some analysis, it is not complete as I haven't had the time to analyse everything.

@Scarblac
The QGA is pretty unpopular compared to most of the opening being played today at the top level.

I have the impression that the main reason why the QGA is not used more at higher level are:

- The dxc5 endgame
- The forcing nature of most  of the other lines in which a well prepared White player can enter a very plain position.

My feeling is that even a traditional Declined Queen's gambit could provide better winning chances because even in draw positions the non-forcing nature of the game gives opportunities to out-manouvre the opponent.

I would say that the Petroff stays to the QGA as the Spanish Berlin stays to the QGD.
However as a drawing weapon I think the QGA is a very good opening. In fact Kasparov and Fischer used the QGA when they were looking for a draw.
As such it should be a perfectly suitable opening also for a weaker player.

NegiRefures, what do you think of 3.e4 e5?

@mrbenoni

Yes, Carlsen did play the QGA vs. Giri, but he is Carlsen and can get away with playing lots if stuff. Lately he has been trying 1... g6 as a way to play for the win. So the QGA is totally fine, but, stuff like the Nimzo/Queens Indian and the Grunfeld are more popular as they are easier to equalize in. I'll post some analysis on 3. e4 lines maybe in a day or so and I'll also check the Ivanchuk games.

The QGA is a perfectly fine opening but at the top level they prefer to play the absolute best lines.

Wang Hao - Ivanchuk and InarKiev - Ivanchuk both 2016 seem to be smooth draws in the 3.e4 variation.
To be noted that also Carlsen has been willing to enter the same variation recently in the game Giri-Carlsen Bilbao Masters 2016.

In your opinion what are the problematic lines and what are  instead the reccomended ones?
Regards & thanks.

Are you saying that the GQA is just not so good? I have noticed that Ivanchuck has played a couple of recent QGA games that ended in very quick draws. If the problem is the central variation ( 3.e4 ) why don't we see more of it after 1.Nf3?
I am really interested in your opinion , thanks.

Hi ChessForum,
I am really wondering why the QGA is not more popular.
Theorically it seems to be in good shape and the theory to learn, compared to other defenses, is relatively small.
Even if the Central variation 3.e4 wasn't sound I don't understand why we don't see more of it at least after 1.Nf3?
To me it seems a very good drawing weapon so why don't GMs use it when Black is fine with a drawn?
What's the expert opinion?