I'll keep i simple. You need a speaker that is pretty much full range, but small enough to be properly placed. Anything the 2X8" woofers needs to be to fat into your room. 2X6" woofers can usually be placed closer to the rear walls without getting boomy. Dual-rear ports allow 4 separate bass tuning settings: both ports open or closed, upper port closed lower port open, and vice versa. I was amazed at how much dialing in could be done that way.
So, Id be looking for Monitor Audio Silver 300 S7, KEF R5.l Meta, Or a good 2.5 way 6.5" design. If your inclined to use the long wall, Maggie 1.7s could work, but they'll chew up a lot of floor space. What I would avoid is anything with too much woofer 2x8" would easily over power the room, and most mini-monitors, they are nearfield-voiced and will tend to sound too small in that room. My experience with KEF LS-50s. Loved them, except they just sounded lost and small -until I got them into a small 8x12 room, then it was "Oh ... that's what they can do." Revel, Golden Ear, and Mertin Logan have very different approaches, but have some interesting speakers in your range - I'd catch a listen to the M-L Electromotion ESL and ESL-X. Exceptional midrange and detail, might be a little bass light for some.