My personal experience is that "room curve" is dependent on the particular speaker in the particular room, ergo no specific curve more suitable than others as a general rule. More controlled directive speakers will naturally have a flatter in-room response and will sound broken if you apply a -10 dB room curve to it. Whatever curve you end up with over the transition area of the room if you measure with MMM technique (or spatial averaging of many different measurement points) with a neutral speaker is the best room curve.
If you have a speaker with lots of problems, a room target is not the way to fix it because you'll likely end up with stupid relationship between direct sound and reflective sound even if it looks good on the measurements in the listening position. Buy better speakers!
If not, you should use the spinorama to fix the speaker with speaker EQ to the extent it's possible. Still sounds bad? Buy better speakers!
When it comes to Dirac my experience is that it sounds a whole lot better if you measure with the couch/sofa settings and use proper spacing in both height and width between measurement points. And measure all 9 points!
This might be different if you have no walls very close to the listening position or speakers, but I find it's a remarkable difference in sound quality compared to one-point or very closely measured points.
If you are lazy with Dirac, it might end up looking like this;
Yep, looks mighty impressive. Sounds awful. Why? Because what you measure and correct for in one point in space is not at all relevant to how the sound field looks or how our ears perceive sound. Example is with Kii Three speakers.
You know that overly smoothed, non-dynamic glassy room EQ sound? Yes, that one. That sound is the result of way too aggressive EQ and in extreme cases it looks like the red curve above.
Here's my onion;
* Measure at many points with decent spacing in both horizontal and vertical space.
* The curves you're presented with will show a clear trend in the room curve. Use that as a basis.
* The room correction will remove quite a bit of energy from the room modes and will sound lean. Compensate by raising the overall bass level.
If you look at the blue curve above you'll see a neutral speaker in a (very) reflective room ending up with something very closely resembling the infamous "Harman curve"
Focus on the difference between the range below 60 and to160 hz and use that as a rough guide of where you should be when you've removed the room modes and their energy. 4-5 dB up from 160 ish can be okay, but keep in mind that this will eat capacity from your speakers.
You thought your little 6 inch woofers were bad-ass? Think again. They have been carried along by the room's awesome modal powers and you've been fooled all this time!
* Oh, do try to measure with and without pillows in place in the sofa/chair just to see how much effect that stuff has around 1-2 khz on the measurements. We don't hear the sofa when we're listening, so why would we EQ it? And keep in mind that a lot of the ripples above 1 khz may very well be from the microphone stand, just ask Amir about that if you don't believe that the ripples between 3-6 khz on my measurements came from a stupid placement of the stand.