which would you buy?

In October 2013 I was auditioning $1500-2500 floorstanders for my living room. I wanted to like the Triton 7 for its folded ribbon tweeter, small footprint, and reasonable price. I had to pass because I couldn't get a good match with the auditioning room, which is about the same size as your room.

The Triton 7 has a lot of bass output, and is probably more at home in a larger room or one with a higher ceiling or open architecture. For your room you might actually get a better match with their Aon 2 or Aon 3. I heard the Aon 3 in a room about your size and it was a good match.

As for the Q900, Kalman Rubinson reviewed it for Stereophile and really liked it.

Also, it might help to know what kinds of music you listen to. I wound up buying Magneplanar 1.7s because they resolved large scale orchestral and choral music better, and their spacing requirements might not work in your 15x15 room.

There are a lot of excellent tower speakers in your price bracket, including the Rega RS3 and RS5, several Focal models (these are transparent, airy, and fast), the Epos K-2. The Monitor Audio Silver Series 6 and Silver Series 8 speakers are excellent, neutral, and fit your budget as well.

MusicDirect has closeout prices on discontinued Focal speakers that put them in your price range. Example: $3200 Focal Chorus 836V for $1799 (demo) or $1899 (unopened stock).

I hope you can audition some Rega RS5s.

I can comment on the Golden Ear Aeon 3s that were addressed earlier (tho not par of original ?) since I have a pair at home.

Due to the engineering of the passive low end radiators, I think they would "fill the room" nicely with sound from high to low frequencies without a struggle. Tho the bass is tuneful and not sloppy at all, itis not tight bass, and for a budget of $1500, it would be near impossible to buy new speaks with tight base for that money, even if buying used speakers at used-equipment prices. I run tubes with the Aeons and am happy with them. Main downside for me (but maybe not you) is the plastic cover. Though it looks nice, I prefer MDF/wood materials.

Good luck!

If you have neighbors below your apt/condo, the stand-mounted Aon 3 would be advantageous over a floorstander by radiating far less directly into the floor. You can also sand-fill many stands, which further damps the speakers' bass notes before they get to the floor.

Personally, for the room size you mention, I preferred the Aon 3s over the Triton 7s. If needed, you can tighten the bass with an amp with a higher damping factor. The GoldenEars sing with tubes, but SS generally controls bass better.

I own the GE 7s, keepers for life.
Very few speakers can give u a taste of HiFi for so little money.
Good enough to compete with $$$$ speakers.
MHO.