That's a perfect sized room for the Canterbury GR. Fantastic midrange; can be supplemented with dual subs if you need to improve the bass extension, but they'll do fine on their own if you don't require hitting 25 Hz and below. The GRF 90 has slightly better bass extension, but according to my dealer the Canterbury GR has better midrange, and you can't fix that with subs - I kind of had the prior-line version of this matchup with Canterbury SE and Yorkminster SE (similar to GRF 90) in my room, and the Canterbury indeed has better mids. I later upgraded to the Canterbury GR model, which is much improved over the SE, and doesn't need supertweeters like the SE did.
The Westminster seems like it would be too big for that room.