Opening help!

Should  I play slav or Queen Indian Defense? against d4.

IT DEPENDS ON YOUR OWN INSIGHT.  Intuition is a wonderful thing in chess that makes the game almost infinite. 

The Queen's Indian defense is a very solid opening. I play it myself sometimes it's bit quite if you are a tactics person, but it is good. I would look at games of Sergei Karjakin for insight. Hope this helped. 

I would play the sneaky attack

Asking a bunch of strangers of varying degrees of knowledge about what you should do is not really a good idea. Do you ride a bus and ask the person in the seat across from you what kind of career you should work toward?

Try them both out. After a while, you'll get a feel for the different kinds of middlegames they lead into—and you'll figure out which one you prefer.

The QID is not an option against 1.d4 Nf6 2. c4 e6 3.Nc3 because now after b6, white can play e4 immediately.

Play something tactical so you become as good as me in tactics!

True! Though, usually QID players also play the Nimzo-Indian, depending on white's opening.

So, after 3.Nc3, black would happily play ...Bb4 and go into a Nimzo.

Or, if white plays 3.Nf3 instead, then black would happily play ...b6 and go into a QID.

Black has fair counterplay after 4.e4, either with 4...Bb4 or 4...Bb7 first. The real problem is the positional approach 4.a3! which is a QID Petrosian, where white can benefit from NOT developing his knight at f3 early.

I hate the idea of "should" in chess. Come up with your own answer. Why not disregard slav and Queen's Indian? Play a defense that makes sense to you. No need to blindly follow someone else's defense.

Ok I am going to focus on what I want to do. 

Ok

Slav was the first one I wanted to learn. Some of the lines were confusing and I didn't like it. With the queen's indian I felt like I didn't have much space and didn't like that too much either. With the queen's gambit declined I didn't like how the bishop was trapped.

So I ended up playing weird stuff most of the time like Chigorin and Benoni. Looking back I wish I had just taken the time to learn the queen's gambit declined.

Personally, I go for the grunfeld cause' I know it the best. but slav works too.

There is a wrong opening, (Damiano loathed the opening tied to his name.) but there isn't a right one.