Most “disappeared” speakers.

You can try out Magnepan LRS with generous 60 days return policy.

Planar speakers are known for disappearing act.

I also pulled the trigger for LRS although I have nice dynamic speakers.

Charney Audio Companion Horns disappear with SS and tube gear. Soundstage is wide, high, and deep with superior tonal balance.

Whichever one I want.

That is not a flippant answer. If you know what you are doing any type of speaker can do this.

I do not recommend buying a set of speakers based on the perception that one will magically do this "disappearing" act better than another. If anyone is trying to sell you a speaker that way, run the opposite direction, because they are B.S.ing you or ignorant. :)

Buy the speaker based on your loving the overall characteristics of the sound. Setup and selection of components and cables will take care of the rest. 

BTW, that is not to say the soundstage characteristics of each will be the same. But, the effect of sensing the speakers have "disappeared" happens when they are setup properly. If you don't get that sense, then you likely have not set them up properly. YMMV