What are the best Room Accustic Treaments members have found?

I  am looking into adding some room acoustic treatments to my room.  I am just looking for advice on some simple room treatments that fellow members found worthy of purchase. 
Just installed GIK diffusors and they work great.  Addressed some smearing and focused up the vocals.  Bit more control of bass.  I also have 6' quarter round ASC treatment in the corners.
There are many great acoustic treatment companies and products out there, but one I am fond of and have worked with at some shows is Acoustic Innovations. They are American Made products, great people to work with, and have very visually appealing products. Much of what they do is theater oriented and they have an incredible client list that they can't publicly disclose.    

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In my RoomPlay Reference room, all GIK except for corner 20" ASC tube (bass) traps that I have had for many years...
IMO, GIK is fairly priced, and they are very friendly & helpful.
No downside of which I am aware.
Jim Smith