Q: Cleaning the iMac screen

If it is new take it back to the store you bought it from and ask them to clean it for you.

What products have you used?

It sounds as though you have already tried to clean the screen with a variety of products.    If that is so it is unfortunate because you should only use a damp microfibre cloth.

See the link here ... How to clean Apple products

I believe you're right about the anti glare facility, though I have not used this model or seen the cleaning recommendations (if they differ from the link I posted).

Now you've clarified what you have done I would agree that a trip to the store is your next move.

I'm sure they'll resolve it.   Do let us know what happens; it is such a useful guide to others.  Thank you for the star.

Spit Shine with the "Provided" Micro Fibre Cloth is the best way.

In Detail:

I had my iMac for a few months now (purchased 1qtr 2014) and I have wondered about cleaning the screen for some time.  The thing is, I to tried a non-abrasive cleaning product but it did not work.  All that did was clean off the dust but left some insanely annoying smudge marks.  I wondered for sometime and inquired a far and wide about cleaning the iMac but no one really had an answer that actually worked. 

Frustrated, I went back to the original box the product and pulled out the manual but also pulled out a black micro fibre cleaning cloth still sealed inside of the box where the keyboard was. I thought, "sure why not".

I continued to perform a really light strokes with the provided cloth and surprisingly all the smudges and streaks started to disappear. I felt as though I was Kratos killing a Titan or something at this point but beauty is the details.

There were some fine peaces of dirt specs stuck on the screen that the cloth would not get off.  I figured I came this far so I wasn't going to give up.

For some odd reason, I thought, "maybe a spit shine D?" .  LOL, no not hocking at the monitor, that would be silly but then again ... Anyways, I did dap a little salvia off my tongue, on to my finger, and then directly on those tough spots where specs were, and wiped it away with the micro fibre cloth with ease.  This was by far the best way I have ever cleaned the d*am* thing since purchase.

i done the same thing deafwing with my imac spit and a very good shine to the spit is free and you never run out lol

lol It really does work though

I recently bought a used iMac from a family with four kids. The screen was really dirty, looked like peanut butter on the screen. First I used Windex to get off the chunks but that left a film. And Apple screen cleaner still left a film. Then I used straight undiluted "cleaning vinegar" (Home Despot) and a microfiber cloth, put the vinegar on the cloth and wiped the screen. Perfect! Crystal clear. No smudges.

Awesome... I tried the vinegar thing  and it is the first time since I bought the iMac  (almost 6 months ago) that it's perfectly clean, No smudges whatsoever.

I almost want to invite everybody to my office so they can see how clean my computer is hahaha.