Which speakers have wide dispersion?

You want uniform dispersion up to a few kilohertz with a gradual reduction in total power response at the high end.

While "omni" speakers are one way to achieve that, designs with controlled directivity (dipoles, wave guides) accomplish the same end-goal with fewer interactions with nearby surfaces and a preservation of detail and "correctness" farther into the room.

Planar speakers don't qualify as dipoles. While they have sound coming off the front and back-sides, they're acoustically large at high frequencies so they suffer lobing problems instead of having an acoustic dipole's nice off-axis behavior (off-axis response is -3dB down from on-axis at 45 degrees, -6dB at 60 degrees, and non-existant by the time you move out to 90 degrees).

I've built pairs of Linkwitz Orions (open baffle) and Plutos (they don't really start getting directive until 2-3KHz. and have no baffle outside the 2" mid-tweeter). The Orions have more reach into the room.

Some time I'll get around to trying a wave guide without the problems that go with horns - Earl Geddes work looks real interesting.

Yeah, by today's standards the 1st-gen Mirage M series is a bit thick-sounding and not so transparent. To make them jump you need to pump them with lots of power with low output impedance, high damping factor, and high current. The 2nd-gen Mxsi series took a significant jump in transparency and clarity; they introduced Mirage's cloth-surround titanium tweeter and bi-wire/biamp capability. The new tweeter added a good dose of speed and airiness up top. The dual speaker terminals rewarded bi-wiring or bi-amping with improved top-to-bottom transparency.

But none of this compares to the entirely new levels of transparency, efficiency, detail, and realistic dispersion of the new OMD series. My brand new OMD-15s trump my old M5si's in every way, and are about 1/3 the mass and bulk.

And some (including professional reviewers) consider Mirage's new flagship OMD-28 to be a standard-setter at its price point ($7500/pair).

"Lifestyle" speakers? I don't think so.

Drew, note that the SoundLabs espoused by Twb2 do not suffer from the narrowed radiation pattern one would normally expect from a large panel. This is because the diaphragm of the SoundLabs is a faceted curve, which radiates over a 90 degree arc (reduced to 45 degrees on some recent models to improve efficiency).

Interesting that you mention Earl Geddes - my own efforts owe a great deal to his work, though I don't think he approves of my bipolar variation.

Duke
dealer/manufacturer

All Vandersteens. The 5a is just sublime, when I have heard it there was not one certain sweet spot. Also, Klipcsh Khorns, really all good horns.

Johnnyb53 hits most of the major points concerning omnis and dipoles. I would add that all speakers bring the room into the mix; omnis make it more obvious. In most ordinary rooms, all speakers do better with a little more 'breathing room' to reduce and delay first reflections.

This weekend I installed a pair of omnidirectional speakers in a loft style apartment—a very difficult room—brick and glass on two walls (front and right), drywall (rear and left), hardwood over concrete floor. Added to this is an asymmetry, wall to the right, open to the left. Fortunately, a high 14' ceiling of open wood joists. The room doesn't sound particularly live, but when playing full orchestra at a good volume, it overwhelmed and started sounding blocked up, although, all other genre sounded great. In this case, pulling the speakers out from the front wall hardly made a difference. Taking some measurements confirmed what I was hearing, so I compensated a little for the asymmetry by adjusting balance, and pulled back the mid & upper bass a couple dB. Still, that room needs more stuff here and there and on the walls for some absorption/diffusion to help tame the room.