I'm not a very positional player and am a beginner so I don't want so many lines.
By: One who started this forum(thats not my username)
Try the king's indian defense (...Nf6, ...g6, ...Bg7, ...d6, ...0-0, ...c5 with the idea to play ...f5 asap). It's a daedalus of theory if you want to play it well, but at the beginner's level, its advantage is that you don't have to think too much of the plan, it's always the same (attacking on the kingside).
Nimzo-Indian Defense is playable but boring. But you can still play it because that opening is not sharp.
Do you consider that the lines from (1.d4 Nf6 2.c4 e6 3.Nc3 Bb4) 4.Qc2 d5 are 'boring' or 'not sharp' ? Allow me to disagree.
The Nimzo-Indian is on the opposite very treacherous at the beginner's level because as Black you need to know how to react to any of White's plan (and White has many choices), otherwise you are heading for a positionally lost endgame. I wouldn't recommend it at all.
The QGD is probably the most solid simple line agains the queens gambit. If you want to get a little more complex, try the slav or the semi-slav.
QGD, but study up on the exhange variation.
Why would a beginner need to study? Just play 1...d5 and if they play 2.c4 continue with 2...e6 or 2...c6. You don't need to know any theory past that, just bring out your pieces and castle. Just one piece of advice: It's usually better to put your knights on f6 and d7 than f6 and c6 in most cases in 1.d4 openings because if you put your knight on c6 you are more vulnerable on the d5 square where you cannot protect it with another pawn.
+1 Don't get caught up in openings because other parts of your game will suffer.
Go for QGD
I actually would also strongly suggest the Slav defense. I used it as a 1700-1900 player playing against titled opponents. Very effective, and the opening moves are very easy considering White really has two main variations he can choose from:
Dutch Stonewall. It is very un-positional, takes 30 minnutes to learn, and is aggresive.
I want an opening for black and not white
A "Stonewall position" can be achieved by either side if they so wish, although it is generally recommended more for black (because it is thought that locking up the center generally takes most of the initiative away from white's first move).There are many systems that share this quality such as the King's Indian Attack.
At your level, studying openings is a complete waste of time which will slow your progress. Study tactics, you win or lose your games due to simple tactics one side overlooked. The only opening knowledge that can help you is the basic general principles.
I would recommend the nimzo complex, with even a small preference for queens indian setup. It would be very exceptional to loose within 20 moves with that opening. I agree that tactics is important for the development of chess skills, but i prefer to answer the question :-)
I suggest u play 1. ....e6 because it can give u manyoptions such as Nimzo Indian QGD french.....But u canalso play 1. ...g6 and Go for KID lines.
If black doesn't want to lose against d4, which one should he/she pick?
QGD or NID/QID?
None of them,cause u will never find an opening that black always wins or white always wins......