Searching for the most "accurate" speaker (below 15K)

vermeer

If you can audition a pair of the Wilson Beseech Geometry Series speakers I think they would work well for you. Yes they are accurate but they also have soul, really enjoyable. Because the cabinets are carbon fiber there will be far less cabinet resonance to interact with your smaller room.

Audiotroy:
Your store has good products, indeed many excellent ones. I’m a fan of ATC, T&A, Legacy, KEF, Stiipoints and many others that it appears you may sell. I actually have no ax to grind. Don’t hijack with never ending "educational" and self promoting pablum and biased dealer opinions and we’ll be fine. Just look at posts by Jonathan Carr, Atmasphere, Audioengr, Kevin Deal (Upscale Audio), Albert Porter (Allnic) and countless others whose opinions many of us here value. They don’t come in to threads that have nothing to do with their products and suggest to OPs to try their products as an alternative to the product at hand. I’m sure they have the urge to talk about their very extensive knowledge and experience and cite chapter and verse of how they came to manufacture or sell what they believe to be the best products of their kind. But they don’t. That is why when they speak, we still listen attentively and often learn.
And you don’t have to claim that you have more integrity than other dealers to sell your stuff. It is simply not necessary. Let the products you sell speak for themselves.
Peace

15k is a generous budget. If your room is 10x14 or smaller suguest a used pair of Wilson Sopha 3's, (and invest difference in S&P spiders), if larger room size then again used Wilson, but larger Sasha's. Both are very accurate, World Class. Enjoy!

Nagra Classic amp and Wilson Benesch Discovery 2, in a 20 square-M room.
This will be my choice and an option for your consideration

As @willemj has pointed out, this is a smallish room. I’m surprised by the number of recommendations for speakers that, though terrific, are likely not the best fit for the room.

@vermeer Can you tell us more about your room? Is your room dedicated for audio or is it a mixed use room? Does it open to other rooms / spaces? Room construction material and height (since you are in Portugal, if it is older construction it is likely different than what is typical in the U.S. and Canada).