When choosing new Speakers, what matters most to you?

@vinylvalet, do you mean measurements or specifications? Specifications are for all intents and purposes meaningless when it comes to loudspeakers. How a speaker is going to perform is based almost entirely on it's design. Frequency response characteristics can be adjusted but to what end? This really needs to be done in the speaker's final location. 

Where is this size phobia coming from?  In order to make low bass a speaker needs to be larger. All those tower speakers with 6" woofers do not make low bass. A speaker's loudness limit is usually determined by it's tweeter. For arguments sake, lets say we have the worlds best 1" dome tweeter. I can put that tweeter in an enclosure with two 6" woofers and have a lovely little tower speaker or bookshelf. I can take the same tweeter and stick it in a much larger enclosure with two 6" midrange drivers and two 12" woofers. Both speakers will go just as loud but which one is going to make better bass? One guess only. Which speaker is going to be more enjoyable to listen to? Does the room size make a difference? The larger speaker is going to sound much better in any size room for two reasons, it makes more and lower bass and there is much less distortion in the midrange because those drivers have been relieved of the long excursions bass requires. As a rule of thumb bigger speakers are better. They are also more expensive so, you get the sour grapes attitude you frequently see and hear on this website. My speakers are HUGE and I love every square inch. There is not a single smaller loudspeaker I would care to own, even ones that are extremely more expensive. As most women know, size is everything:)

@imhififan, I can put 20.7s in a closet and make then sound good. The only limit on speaker size is the width of the door. Computer speakers in a department store will certainly not work well.

Specifications and measurements are two entirely separate issues. Specifications can lie, measurements do not. How many of you out there in Audiogon Land actually measure your systems? 

A loudspeaker's design will tell you a lot about how it functions in certain respects. It will not tell you how it sounds.

A loudspeaker will sound different in two different rooms because the rooms sound different.

In thinking about my own experience, I just bought a new pair of loudspeakers and I had never been in the same room with a pair. Not only this but I had them built to a specification that had never been done before. Fortunately, they are performing beyond all expectation. I have done similar experiments before resulting in total failure. Experience is the best teacher. In truth I have had decades of experience with similar loudspeakers so I knew exactly how they would perform. This is determined by the physical characteristics of the speaker. I was not worried about how they sounded because I can make them sound however I like. But, if a speaker can not image no amount of monkeying around is going to get it to do so.

You have to determine what you expect out of a loudspeaker and  the physical characteristics such a speaker should have. The way a speaker images, the size of it's sound stage, the way it radiates sound are not accidental. They are by design.

A speaker's frequency response will vary wildly from one room to the next. In this day and age with DSP amplitude, time and phase are easy to deal with. You measure and tell the computer what you want it to do. 

Expectations are different. I expect a system to be able to simulate the sound and sensations of a live performance given the right program source and with any genre. A system that struggles to get down to 40 Hz can not do this. It is missing an entire octave!  3dB down at 40 Hz/1 meter is 10 dB down at 4 meters. So much for bass. Only line source arrays produce life sized images and they are inherently more efficient radiators of sound into the environment. They sound more powerful. The room is much less important to a line source dipole. They radiate in a very specific and predictable pattern and positioned correctly have far less interaction with the room. You hear more of the music and less of the room. Only horns are as predictable.