The best speaker I ever heard was the Linkwitz Orion. Being an active crossovered speaker with separate amplification for each driver and also being a dipole, you need to place it out into the room by at least 3-4 feet. But if you can do that, you will be amazed at the huge soundstage, the great imaging, and a sweet spot that is enormous. It sounds great even anywhere in a room. Go to the Linkwitzlab.com site.
As far as classic loudspeakers go, the Devore line, with the top of the line Silverbacks are beyond incredible. The next down the line in the Gibbon series is the Gibbon 9 at MSRP $6,500/pr. In a medium-sized room it is amazingly wonderful and is so easy to drive that it thrives on low-powered tube amplification, such as Leben, Shindo, and much less expensive tube amps.
Greg