Speakers known for great midrange.

Best mid-range I ever heard was the old model Alon Phalanx

The Alón Phalanx/Poseidon Loudspeaker System is to this day the best mid-range sound I ever heard.  I also jut heard them recently, why I didn't buy them I don't know.

Happy Listening/

I personally own INT-25 paired with Sonus Faber Olympica 2. I'm very pleased with the music filling my room. I would characterize the sound as lush, inviting, engaging, very transparent, relaxed, airy.  I prefer the original Olympica series as the new one I wont say sound brighter but colder to my ears.   

Arguably one of the best mid-ranges is found in the Vandersteen KENTO and Model 7.  Unfortunately, these are floor-standing speakers so the monitor requirement does not apply.  If it were ins a monitor it would be expensive. https://youtu.be/T2pvz6RDBCE 

I’m thinking about going with the CSS Audio 1TDX prebuilt stand mounts. I haven’t seen a bad review of these yet. Or I might spring for the 2TDX towers. 

Check out Wavetouch V2 speaker's midrange.

Alex/Wavetouch audio