Which variation of QGD to play as black?

I play the qgd since 2005 or so with a small break only, there i changed to the slav. Sadlers book was fine when i started to play it. You read much about the typical plans and structures. E. g. in the exchange variation black wants to play Bf5 with much effort sometimes or you want to play Bd6 against white setups with Bf4. Sometimes you get theses moves "for free" against inferior move orders. One of my teammates plays the exchange variation on move three instead of the optimal 3. Nc3 Nf6 (or 3.... Be7 4. cxd5) 4. cxd5 move order. After 3. cxd5?! exd5 4. Nc3 black plays 4... c6! and  has time for Bf5 and / or 5. Bf4 Bd6!. Some games went 3. Nc3 Nf6 4. Bg5 Be7 5. cxd5?! Nxd5! with a good semi-tarrasch. 

To master the gqd you have to understand these things. White often wonders much about the kings indian, relexes too much against the qgd and then you win.

There are more often played sidelines today, e. g. setups with e2-e3 before Bf4/Bg5, the catalan is very popular and everything instead of 2. c4. Ntirlis book covers nearly all of that stuff and is therefore the best book on that topic, even if you don't like his mainline.

The links are to book samples and a book review. Again, here is a game from the Move by Move book, providing some indication of what it advocates:
http://www.chessgames.com/perl/chessgame?gid=1478323

Queen's Gambit Declined by Matthew Sadler (2000)
https://web.archive.org/web/20140708234438/http://www.chesscafe.com/text/hansen15.txt

Playing 1 d4 d5 by Ntirlis
https://www.chess.com/blog/pfren/playing-1-d5-d5-a-classical-repertoire
https://www.qualitychess.co.uk/ebooks/Playing1d4d5-excerpt.pdf

Ntirlis "Playing 1.d4 d5" is particularly good. If understand the exchange variation chapters will give your club player opponents a lot of problems. If don't like Kramnik's improved classical line nb-d7 then h6 and quick c5, can easily replace it with the Lasker, which is a lot more straightforward, or the Tartakower. Actually part of the suggested rep tranposes to a line of Tartakower with white playing Bd3, which I thought was quite testing, Could be wrong about that.

Hmmmm, crappy or dubious gambits, which i always play, doesnt count to "openings"?!?

Thats new for me...but thanks for the hint...i will contact the admin to erase all threads about the Blackmar-Diemer and the Latvian from this sub-forum 

Beside that, i´ll manage to beat 1800+ with sidelines of the Englund (not with the boring, lame and passive main line) like the Blackburne-Hartlaub or the Soller-Gambit, sometimes you win, sometimes you lose, but studying the QGD will not make you become a better chess player, but feel free to try it...

I never said that dubious gambits or sidelines don't count as openings. I have no idea where you got that from.

I literally quoted your comment "why do you want to waste your time to learn tons of theory lines" and asked why you're in the opening subforum if that's your attitude towards openings. 

Oddly enough, there is a fairly recent book (My First Chess Opening Repertoire for Black) that, if I remember correctly, suggests the Albin Counter Gambit as part of a way "to forge a digestible repertoire without expending too much energy on it".

https://www.newinchess.com/media/wysiwyg/product_pdf/9050.pdf

Moret also wrote, "There will always be time, later, to come to the main opening variations recommended by theory", so it would seem that it was recognised that, at some point, a player might feel ready to move on to something like the QGD.

I thunk the most instructive would not be the moves but on the idea behind the moves.

I have never found this in any chess book. Yes there is the narrative but not the ideas why you are taught to play a certain way. Perhaps this is impossible as it depends on the opening but surely every opening has an idea and development of that idea or am I missing something?

There are plenty of opening books that go over the strategic themes in the middle game (and sometimes the endgame!) that tend to come from particular openings. These days, it's only the badly written ones that don't, though in the old days, there were a lot of "database dump" books that just gave you tons of moves with minimal explanation. With everyone having computers and that stuff more readily available on the internet, those types of books are much less commonly published in the last 10 years.

East or West orthodox defence is the best

it is a good positional line and if u want any help on the QG ask private message me(3 dollars per question. LOL! just joking)

https://www.chess.com/forum/view/chess-openings/the-lifetime-repertoire-reliable-ambitious

If this topic caught your attention, I suggest you look at the detailed article I wrote.