The Nimzo indian is interesting and has a lot of Grandmaster recommendation but its a lot more subtle than other defences such as KID.
"Best" defense vs. 1.d4

FWIW -- I play the Dutch (with an early ...e6), Nimzo Indian, Queen's Indian and occasionally the English (1...b6). I have at least one book on all of these and spend far too much time away from them. :)
Good luck!
ZV

I think the Nimzo or the Slav are your best chances to equalize, but if you prefer to attack and play from an often slightly worse position, then the KID, the benko gambit, or the benoni are great choices for a sharp game.

I would reccomend the Nizmo- Indian, Queens indian, and Bogo indian, The Tarrasch, Semi-Tarrasch, or the Grundfeld, I also like Chigorin's defense if you look for something offbeat. I like the semi-slav but it can lead to very complex positions, and really I shouldn't play it because because some of the ideas are alittle over my head.
But what other openings do like to play, that would help in selecting an opening to play against d4.
Well, as white I usually play d4, leading into the queen's gambit or the indian defenses. But I've also been trying to pick up the Colle and the Ruy. As black I usually play the Caro-Kann, but occasionally the Sicilian, vs e4 and the slav vs d4.

If you like the caro kann then the slav should suit you, you can also play 1...c6 after 1.d4 to give white the chance to transpose into the caro kann.

If you want some interesting play against the Queen's Gambit, try the Chigorin Defense as pvmike mentioned. It can be fairly sharp, but it is worthwhile to look into.

I play the Nimzo Indian vs White, but as a d4 player as white mostly I see the QGD or the Slav. I rarely see the Indian defenses. I like to play the Grunfeld every once in a while if I am in the mood for it.
Just looking for opinions on what people suggest playing vs. 1. d4. I started with the QGD, but now I tend towards the Slav, but a lot of people seem to play the Nimzo-Indian. Thanks.