The best speaker for a small room...at any price point.

My current favorite speaker TAD ME-1 small stand mount with a big sound.

Ilumnia Vocalis

I have Focal Aria 926 speakers in a small room and they sound wonderful driven by two Schiit Vidar Monoblocks and a Mytek Brooklyn DAC+ / PreAmp.  They will not overwhelm a small space but retain excellent detail, transparency, and fast response while remaining very neutral and not bass heavy (I find key for something like a small guest bedroom or study that is close to other bedrooms).  All recommendations made thus far are great options, it comes down to your actual space, purpose, preference and parameters/limitations.  Happy hunting!

@yyzsantabarbara I have Focal Electra 1028 Be speakers in my primary listening system in a large room (20' x 30') and could not imagine them in a smaller space.  The Kanto is the replacement for the Electra, so I would expect a similar performance/price ratio.

Pulsars, but look at the Usher lineup. Oh, Living Voice too.