Hi,
I would say the Middle T's for sure given the room size. A lot will depend on how loud you listen to your music. The Model T can be used in a smaller room than you would think because the Sound Power Response is equal in all directions but the Middle T is a safer bet if the room tends to load up easily.
The power handling capability of the Model T is really the only benefit over the Middle T. The sonic characteristics, the crossover points and the listening window and sound power are all similar on all the different T models.
I did a show in Toronto at a dealer last Saturday in a room similar size to yours and the Middle T's sounded superb
Hope this helps.
james