Thank you Abba, I already know the Slav and the Budapest Gambit (I don't consider the BG a very good opening, but sometimes I play it for fun).
First I would like to improove my play against the King's Indian, I know that is played at all levels but against it I have no experience.

As regards the Queen's Indian, I've always played "fianchettoing" my light square Bishop, but I saw on a book about d4 repertoire that the author advised to not play the bishop on g2, what do you think about?

After 1.d4 Nf6 2.c4 e6 I play 3.Nf3, so I avoid the Nimzo-Indian, if I'm not wrong, I have no need to prepare myself about this opening.

Well... the Grunfeld... I've never faced an opponent that uses this defense

The Dutch is not so common at high levels but I now that is played at lower levels, I had to play against it a couple of times. I played not 2.c4, but 2.g3, because I saw it in a book, but I know that is not enough and I must have a deeper knowledge about the Dutch!

Then I have to consider the Tarrasch, the Queen's Gambit, Accepted and Declined, against them I usually develop the pieces without knowing if I'm following the theoretical lines or not.

I'm about 1700elo, so I think that is the moment to develop deeply my opening knowledge. Can you advice me, please, wich variations are better to face these "main" defenses?