Earlier this year I bought a pair of floorstanding ProAc Response 2.5s for my room which is just about a foot bigger than yours in each direction except for the height which is the same.
I have tons of stuff in my room, so its effective size is actually much smaller, but the floorstanders sound great. Prior to that I was using ProAc 1SC and Tab 50 Sig monitors, but the full range ProAcs actually disappear better while doing everything else as good or better.
I don't know the configuration of the elements in your room, but If you use monitors with a sub, having the sub separately might allow more placement possibilities and make it easier to tune the bass. Sometimes people struggle with floorstanders in a room like ours especially if the speakers they're using don't like being near side or back walls.
You might want to first consider designs like Totem or Sonus Faber which are less rear wall finicky than ProAcs which use rear ports. I'm lucky because the rear of my 2.5s face openings in the room.
Good luck!
