Most high-quality loudspeakers are 4-Ohms

Mapman, I some level I think you've hit the heart of the matter with "I don't think impedance alone is a relaible indicator of "high quality", assuming you take proper matching of the amp into consideration...."
While we can't truly seperate amps from speakers, the OP question offers food for thought on the issue re: impedance and the quality of speakers. If we try for just a moment to stay focused on speakers alone, the OP's question isn't as silly as it might first appear.
I suspect that many speakers that are designed to be more effecient are in fact not so due to inherently superior drivers or other design parameters but, done so that they can better accomodate particular amplifiers and that course of action might just very well compromise the ability of the very speakers themsleves.
There are some here that think that less effecient speakers and big ss amps are silly. I would argure that that's no sillier than less efficent, small tube amps driving big speakers.
My experience tells me that the differences between speakers is greater than the differences between amps regardless of the amps technology.
YMMV, everyones tastes are different, and the marketplace has almost everything for almost everyone. Enjoy, regardless of the path you choose.

I suppose another way to look at it is that higher impedance speakers are a safer bet to be able to be driven properly with a wider range of amplifiers.

So if you do not want to have to worry as much about matching an amp to speakers, 16 ohm speakers may be the way to go. However, given the current state of the high end audio market today, expect to pay a premium for those high impedance speakers compared to those "higher risk" designs with lower impedance and similar performance potential that may not sing with just any amp.

Mapman, actually you've gone too far in the opposite direction. Most ss amps aren't at their best into 16 Ohms. Remember that a ss amps that doubles down from 8 Ohms also halves up from 8 Ohms. The safe bet for ultimate amp compatbility would probably be around 8 Ohms, and perhaps 6 Ohms for mass market amps.

Like I use mass market drivers.

Unsound you said [I suspect that many speakers that are designed to be more effecient are in fact not so due to inherently superior drivers or other design parameters but, done so that they can better accomodate particular amplifiers and that course of action might just very well compromise the ability of the very speakers themsleves] You can have this opinion all you like but if you understood even a wee bit about transducer or loudspeaker design you would understand how wrong you are.