Multiple options and approaches are possible in that room, depending upon your level of "purism". If you prefer a simple setup with flexibility, consider using active speakers with DSP and a frontend of your choice. Please bear in mind that these observations come from someone accustomed to using 15" speakers, so my sense of what is acceptable in a living room might be a bit skewed. Looking at your room, I'd suggest placing the speakers against the back wall and using DSP to align the bass if necessary. Utilizing room gain can be advantageous! If you're against DSP, opt for speakers that perform well near a wall, potentially sealed ones. Adjust the seating to be closer to the point between the two windows. Install diffusers on the sidewall between the windows and absorption on the first reflection points. Be careful of too much treatments! Depending on your speakers, try moving them further apart and angling them inwards to minimize sidewall reflections. Experiment with extreme toe-in. If feasible, choose the largest speakers that fit. Bigger speakers usually provide better results. Larger speakers offer improved directivity and are less influenced by room acoustics than smaller ones. Subwoofers could be beneficial. Align them with the speakers if placed against the same wall, reducing alignment issues. I would not use a speaker system without subwoofers. Be prepared to learn REW (Room EQ Wizard) and familiarize yourself with your room. This is where significant savings can be achieved ,as you realize that the room is at least as important as the speakers. How moving things around can have a big impact on perceived sound! IMO Speaker setups involve more variables compared to headphones. (speaker placement, listener placement). However, you can "tune" their sound more as you can move things around. Personally, I prefer employing full-range DSP for all my speakers. Achieving good outcomes can be intricate and time-consuming. Nevertheless, I've been content with my speakers for quite some time now and haven't felt the urge to upgrade, so there is that.