Of the four mentioned i would go with the Proac but i would also consider a large classic british monitor like the large harbeth or spendor to fill that large of space. You need a speaker with a large woofer and a bigger cabinet face to project the sound in a room of that size. You may even want to listen to some very good vintage systems in that size room, what you hear may really surprise you.
Proac K6 Signature, Sonus Faber Amati Tradition,Verity Audio Amadis, Kharma DB-9
...if you were me and you played rock and roll like the Stones, the Allman Brothers, John Mellencamp but also played singer songwriters like ; Bonnie Raitt, Jackson Brown, Waylon Jennings, Josh Ritter but also loved jazz like Pat Methaney, Return to Forever, Cannonball Adderley. In a room that is 16 wide and 30 deep with cathedral ceilings and all Accuphase separates with the amp being a 60 watt pure class A design …...which one would pick ? I have narrowed it down to those 4 brands - don't care what you have or had just anybody's thoughts on those 4 Particular speakers. Thank you and stay well and safe out there !