Most “disappeared” speakers.

You need to master set your new speakers regardless of what you buy.

I would highly recommend buying Salk Audio's Song3 Encore tower speakers.  Jim Salk sells direct.  He can then afford to build his speakers with the highest quality drivers.  The song3's deliver a bass extension of 25 HZ and are just incredible.  I will upgrading to these within the next two years.  I would suggest calling Jim Salk to discuss what speakers he would recommend for your space.  He is one of the most knowledgeable people in the industry and he is extremely honest.  Tell him Larry Edwards sent you.

Most high-end speakers will disappear in a proper room. Monitors more so than floor standers.

My $250 used and vintage Spica TC50 monitors speakers.  Wonderful in this regard. 

Joseph Audio speakers disappear and image with the best of them.  I also like ProAc and Vandersteen for these reasons, but there's just something special in this regard from JA speakers.  Also agree Audio Physic speakers excel in this area, and Avalon speakers also impressed me in this regard.  I think Verity Audio and Gershman speakers are also very good in these areas as well. 

Omnidirectional speakers