I think the QGD is a pretty good choice for a relative beginner. You have to decied if you want to play more modern setupd( like KI, Nimzo etc.) or if you want to establish in the center early. I would recommend to give QGD with a b6/Bb7 Setup another try.
Black versus 1.d4 help!

Depends on what you like.
Nimzo setups are very solid and versatile but have a lot of theory to study up on because they are so flexible, these include the Nimzo Indian, Queens Indian and the Bogo Indian basically.
The Kings Indian is very popular, still has a lot of theory but perhaps not as much. A slightly more aggressive response to d4. This is a very tactical opening. Think of it like a shark, if you stop moving you die.
The Dutch is pretty good albeit risky, though you really should know what you are doing. The Classical is pretty good, the Leningrad and Stonewall are good as well but you have to know what to do or you'll be in trouble quickly, expect dynamic games.
Queens Gambit declined and the Slav are extremely solid. QGD is kind of where everyone starts when defending against d4, you can never really go wrong. Although you will get somewhat slower games with a lot of maneuvering.
The Benoni and it's variations is interesting to say the least. It's a little difficult to play but it does lead to imbalanced and dynamic positions. Something to play for the win.
The Grunfeld defense is very tricky. It's very sharp and dynamic, but could give black problems in the long run if not careful. A beast of an opening in my opinion.
The Englund gambit is stupid.
The Albin Counter Gambit is a very aggressive response when white tries to go for the Queens Gambit. It's very uncommon though. I don't like it personally but there are some traps and attacking chances.
The Chigorin defense is also solid enough. Though it's not that popular and I don't much about it. From what I can tell it's playable but you will have to give up the bishop pair relatively early. If anything its worth a try.
There are a couple more and there are some freaky sidelines but this is basically it. They are all fine but you will need to put some work in, studying and practising. I used to play the Czech Benoni then made a switch to the Nimzo/QID. Experiment a bit see what you like.
Nimzo all the way for newbies!
Why the Nimzo Indian is the best chess opening move against 1.d4
- Black is able to profit from the pin by compromising White’s pawn structure
- The pin prevents White plans of extending in the center.
- Black has used only one pawn move and is on his way to complete his kingside development.
- Black is more flexible and has many options of countering in the center.
- White often has to scurry to complete his development.
This flexibility of plans and the ability of damaging White’s pawn structure are part of what makes the Nimzo Indian such a strong and powerful reply to the 1.d4
Click here to learn more about the Nimzo

Well I was always fond of the Grunfield Defense. It a little outdated but its always fun to use as a switch up against D4

I rather liked the Queen's Gambit Declined Cambridge Springs variation.
One of the things that can happen is white gets all concerned about the queen side diagonal pressure and forgets that Bg5 is hanging to ... Qa5 without the black d-pawn on [d5] square.
The number of times white played 8. Bd3 in my salad days, along with the trap shown you would not believe.

Is that still a viable defense against modern D4 openings? I remember using it in the 70's and it really was kinda lacking.

For a beginner I'd recommend nimzo Indian. Black plays actively against whites bishop pair. Not too big of an imbalance

I like the nimzo. But I have noticed that a lot of D4 players are avoiding it by not developing the Queens knight. Instead going with the East Indian system with 3. NF3. It only gives white 30+ % win ratio so its not a killer move.

I have never seen anyone consider the Old Indian to be "inferior"
but what you said about inferior openings leading to positions you understand being better is correct.

I play mostly daily chess, but I am a 1.d4 player so I can say that I find the Nimzo-Indian is a challenge to play against, but I probably wouldn't feel comfortable playing with it in a live time control. I really do think QGD is good though. It's not a system, but I think you can get a good sense of where to develop pieces without making too deep of calculations. Slav is good too. I think there are a lot of very playable options for black.

In QGD you want to trade the minor pieces into a draw (sorry QGD players that play Tartakower, I'm generalizing the orthodox)

CleanTablet wrote:
Is that still a viable defense against modern D4 openings? I remember using it in the 70's and it really was kinda lacking.
It does say "Beginner" but if Carlsen in 2013 gave it whirl ...

Besides if you look here:
https://www.chess.com/live/game/5246068646?username=twelfthknight1
It do seem @TwelfthKnight likes the trappy pin style of play. All be in that game he exploited a bad pin.
Hope you're doing well, was wondering if anyone may be able to give me some recommendations. I am relatively new to opening theory etc., so I am just beginning to build my first 'repertoire' if you will. As white I tend to play the London/Jobava London System, while as black I play the Scandinavian against 1.e4. However, I haven't found a defense/system against d4 which I feel comfortable with yet (I have tried the Kings' Indian, QGD, the Slav, heck even the Englund Gambit!). I think, for example, with the KID, I was okay when white played the main line setups (e4,d4,c4,Nf3,Nf6) but struggled against deviations (this is why I prefer 'system openings' where I can learn and implement ideas rather than other theoretical openings which I simply do not have the time to learn in full.
Any suggestions/advice would be much appreciated. Thank you in advance!
Tom