What William suggested was changing your layout to a system like this which shares a similar spacial geometry to what you have:
While that would give you the best sound, I am not a big fan of that approach. I think its ridiculous to block a window view with AV equipment, and I am even a pretty big enthusiast of speakers and great sound. I think you can get some pretty good sound with some more modest modifications to your present layout.
First of all, for your present system, I would pull the couch up some, maybe two to three feet up away from the back wall. At the moment you are sitting in acoustically compromised position. You are getting strong acoustic reflections from the back wall since your ears are so close to it. Getting away from the wall should help. Also, if this can be tolerated, remove the coffee table from inbetween the sofa and sound system. perhaps move it to and endtable position or something, but it is a hard first reflection between you and the speakers that will end up causing problems with the frequency response at the listening position.
One more thing you might look into after that to further improve your acoustic situation is placing some kind of acoustic treatment on the backwalls behind your listening position, perhaps some kind of diffuser. Diffusers can be expensive so I would look into DIY diffusers.
One you get your sofa away from the backwall, surround speakers make a lot more sense. I am not sure I would go for 7.1 at that point, as you do not want to be too close to any of the surround speakers. I would go for 5.1. But maybe 5.1.2 is worth a try of you can place speakers on the opposite side slanted wall if they can be made to aim right at your listening position. It almost looks like that is possible. What would be good about that is that you could use an in-wall speaker for the Atmos height channel as opposed to an in-ceiling; in-walls speakers are an inherently less compromised design than in-ceiling speakers.
For speaker brands, there is a lot of good choices. RBH, Ascend Acoustics, Outlaw Audio, Hsu Research, Paradigm, SVS, JBL, Revel, RSL, Philharmonic, among others. As I mentioned before, I think bookshelf speakers would make more sense in that situation than towers, although if you cranking the volume really loud, tower speakers might make more sense, although there are bookshelf speakers and LCRs that can still handle wide dynamics, like the
Hsu CCB-8,
Ascend CMT-340se,
RBH R-515/
R-515E, etc.
For subwoofers, I would look at what can be had from Hsu Research, Outlaw Audio, SVS, and Monoprice Monolith. For AVRs, I would look at offerings from Denon, Marantz, and Yamaha that fit your budget and criteria.
