What is the best Sasha or Maxx3 ?

If your speakers are placed along the long wall, the Maxx 3's might not work. They are ~2 feet deep and should be a few feet off the rear wall (say 5' now) and your chair may sit a couple off the wall (1-2) this would put your listening distance ~8' and the Maxx 3's can't accommodate such a close position.

Now of they are on the shorter wall they will play louder and offer more dynamics and taller soundstage. (I'm torn between these two as well!!)

Love to hear what you end up with and why!

Concur with Kurt tank. The Sasha will be plenty and you will likely have to treat the room (thick rug, bass traps in front corners and panels at first reflection points at the least and maybe even behind your listening position).

My room is roughly 14' x 16.5' x 9.5 high. I have WP7 at the moment but am considering Maxx 2's. I just was emailing with Wilson today and they felt Maxx's would be "stellar" in my room so I do not think room size is an issue for you and neither does Wilson Audio.

In regards to the comment above about placement 5' off the backwall, I would strongly disagree. The way Wilson does/recommends setup, it is completely dependent on room. In my case, they fell only 1 ft from the backwall, aprox 2' from sidewall. This is not uncommon at all according to Wilson trained setup guys with many many years experience.