Queen's Gambit Declined is a good defense, but you can play the Tartakower variation or Ragozin for variety---you can also play the QGD against the English Opening most of the time, thus saving some opening study time.
Best Black opening against 1.d4

The Benoni is probably the sharpest choice by black, in which play usually revolves around the center. It’s also the least beginner-friendly one, though. Cramped up positions and tactical everything might not be what you want.
The Grünfield is particularly popular at higher levels. Sound and fun to play. It’s heavily theorized so there are a lot to remember, but that doesn’t mean you can’t have fun without knowing every single line.
As a lowly 1300 +/- player OTB, I am looking for a new opening against 1. d4. I normally play QGD - Lasker’s Defense, but am getting tired of it.
I’d like the opportunity to breathe new life into an opening that has good fighting chances for Black and is reputable at the same time.
All suggestions will be seriously considered as I’m looking to take the time and effort to improve.
Cheers,
James