Best $10-15K bookshelf speaker?

Vimberg makes wonderful speakers for sure, great suggestion!

Personally, I don’t like not having a full range sound. For my clients in your particular situation, I like to recommend the Vivid Audio Kaya 25. It’s a fantastic pair of speakers that don’t take up any more space than a pair of standmounts and stands. They are magnificently coherent, have wide dispersion / sweet spot, work with all sorts of rooms, and can just completely disappear. Best of it all, they are not that heavy (55lb or so) and the cabinet is typically twice as big as large bookshelf speakers, so the bass is more palpable.

I should also mention that I think the Kaya 25 is one of the sexier speakers on the market, especially in custom finishes. The one I recently ordered for my floor are in a Porsche Agate Grey and it makes a nice improvement visually over other Vivids I have that are in their stock colors.

$15k gets you the Dutch & Dutch 8c loudspeaker system.  That includes an active crossover, built-in amplification, DSP EQ and DAC.  All you need is a streamer and your system is complete.  They have the most extraordinary imaging Iʻve ever heard in a loudspeaker.

I concur with @jastralfu 

Marten Parker Duo.  I think it will be hard to beat the open and airy sound of this brand.  

Wilson Benesch p1.0.  

$15,000 for a bookshelf speaker? Really?