Semi-Slav or Nimzo-Indian Defence

Hello, I am choosing between two good defences against 1.d4.

I had played the Semi-Slav which is a solid opening, but it's hard to develop the light square bishop. I think that Meran variations gives an amazing position for both sides. And against 5.Bg5 I play the Cambridge Springs (5...Nbd7 6.e3 Qa5), here opponents usually avoid the main lines and it leads to positon where it is very hard to develop the bishop on a good square and white gets a little bit more space and a strong bishop pair. Also white can play sidelines like 5.Bf4 and 5.g3 where the engine recommends to take on c4 but it gives up the center control and I found moves line Ne5 annoying for black. In some games I got a exellent pieces placement but had no real plans, I think this is due to my passive play, and it's one of my biggest weaknesses. I am also thinking to buy the Sam Shankland course on Chessable on this opening.

I had never tryed the Nimzo-Indian as black, but had analysed some games with this opening. As white, I was playing 3.Nc3 and going for the Nimzo, for me it was the most annoying defence where I couldn't find any advantage for white. The Nimzo lets black to develop the king side very quickly and black continues with setups with b6 Bb7, and d6 Nbd7. I know that black can play different setups like Ne4 followed by f5 or be playing for e5 like in the Bogo-Indian. At the end I want to say that this opening can lead to a positionnal game or a very sharp one. 

You could play both.

1.d4 Nf6 2.c4 e6 and now:

3.Nc3 Bb4

3.Nf3 d5 4.Nc3 c6

@1

"Semi-Slav or Nimzo-Indian Defence"
++ Both are good, pick one and stick to it.

"positon where it is very hard to develop the bishop"
++ White has the same problem with Bc1 as black with Bc8.

"The Nimzo lets black to develop the king side very quickly"
++ Yes, but black often has to give up the bishop's pair, and white often gets a strong center c4-d4-e4-f3 and a strong attack on black's king.

I like 👍 them both, but I recommend 👌 the Nimzo-Indian Defence

Remember that 💯 both are for black ⚫️

indeed. I don't play either, but respectfully I would play the Nimzo as a Main. It seems you're kind of leaning that way. Not that you can't have a back up or secondary (using the Semi-Slav). Thing is, your goal should be to strive to be a Flexible Player... Not struggle to find a Flexible Opening. Develop your Defensive Prowess~regardless of the Opening. White or Black. Last thing, drawing with Black is actually a "win". Think on that & best wishes.