Size, shape of room and isolation is critical too. 17 years ago I included a listening room in the basement of the house we built. Followed Fibonacci ratios: 8ft x 13ft x 21ft and insulated it well, in a very practical approach. My only downfall was using recessed light cans in the ceiling. Even with 12" of fiberglass batts in the ceiling I still hear footsteps/etc. from above, but overall it's spooky quiet in there. From there added 10 GIK 2ft x 4ft 244 panels, which frankly in my room do little good compared to other rooms. Six of the panels are "full range" at all the first reflection points, four panels are "bass traps" straddling the front corners (moving them around makes little difference). Then added 3 subwoofers in semi-random locations. With all that tried adding bass DSP a couple of times to little effect.
Other significant points includes the setup. I use mid-field with loudspeakers 5ft from front wall, 2ft from side walls, and 7ft from the listening position aimed to cross 2ft in front of the listening position as well as proper loudspeaker design. Proper design opens a whole can of worms that I won't get into but will say that I commissioned my loudspeakers 18 years ago and they suit me quite well. Another factor to setup is the amount of stuff you have between the loudspeakers. Soundstage cannot penetrate solid masses, so I minimize what I have between while keeping the wires short.
As always I recommend reading Floyd Toole's "Sound Reproduction" (either/both editions) to learn how rooms inherently create huge (up to 30 dB) bass peaks/dips and the advantages of using multiple subwoofers.