Best full range loudspeaker for the used price of 10 to 13,000 dollars

I will not tell you about what I think or hear say, will just tell you about what I know.
Best fullrange I know is Tannoy Westminster GR, but good luck with finding a second hand pair for $13,000.
Many stated in threads here are good, but one beats them all without the shadow of a doubt in my opinion and would beat many at over $25,000, it is the XTZ Divine Alpha. Just plain amazing for the price, $8,000 new. Swedish stuff, all first batches of production are pre-sold. These will absolutely dazzle you or i know nothing after 30years of audio mania.

"THE BEST" in speaker performance is subjective. To properly compare A vs B variables must be controlled. Ideally listening should be blind where the listener has no idea of the brand or physical characteristics. Connections are made to the same components with the same interconnect. Comparisons are done quickly to eliminate the loss of acoustic memory we all experience. Ultimately the goal should be to accurately reproduce the original image. Achieving this goal results in a satisfying experience as the listener is exposed to to new and different types of sound. The speaker should be relatively tolerant of its environment. REVEL has a custom platform allowing them to quickly compare speakers using the above guidelines. With this in mind the REVEL speaker is an excellent place to start. Vast R&D resources, (Harman Luxury Audio Group), and excellent guidance from Director of Technology Kevin Voecks, result in a superb speaker at all price points. Voecks has an outstanding pedigree and the results are evident.
Nuff Said.             

hddg - indeed - Tannoy Westminster GR by far... but... who’s going to spend that much money on speakers!

And... who is going to have the space and muscle to set them up properly!

If you can find them and are willing to invest a little more say $18K buy a pair of Wilson MAXX II's.  You will be amazed and never look back.

Dynaudio C4