In listening to your system(s)...what is most crucial to your enjoyment?

In growing up around live musicians and instruments, the authenticity of sound, timbre ( Timbre is French in origin, which is apparent in its pronunciation: it is often pronounced \TAM-ber\ and, with a more French-influenced second syllable, \TAM-bruh\. ... And timbre may also be correctly pronounced just like timber as \TIM-ber\) ...a search finds diversity to the definition of timbre.  For me, it ties to "my truth" when I hear non-amplified instrument or group of instruments, voice or voices presented before me.  Changes to my system either get me closer or further from my truth.  Emphasis "my truth" because I've come to believe, like our other senses, it differs among us, leaving "experts" to theirs, some of which seem to "fit" mine.  It's fun when that happens.  Robert E Greene of TAS and Art Dudley of Phile seem to have advised me towards my truth over the years (with bits of disagreement here and there) but, they have steered me well, thanks.  What do you find crucial?
Increasingly I value the flow or continuity in music, that sense that you are hearing the continuing uninterrupted sequence of a musicians choices without spotlighting, added emphasis or color.  It’s actually a tricky thing for systems to realize but once you get it it’s very apparent. This should be true of all players in the mix, even those buried in the background. 
Timbre and realistic dynamics are most important to me.I've also spent a lot of time around musicians.My son teaches and plays professionally also.It's gotta sound real :)
To me, most of the audiophile attributes go out the window when it’s "right." I’m drawn into the performance and the sonic attributes are all simply ways of describing different aspects of the sound, none of which are of more importance if it ’sounds real’- something I only achieve on occasion when the recording and the system align in the room. Sure, I can examine each of those different attributes and describe them, but they are all just facets of the whole and none is the primary reason why the illusion is so convincing at times.
In terms of my personal sense of the importance of these attributes, that has evolved over time- midrange was always the most important to me, grainless, see-through. I learned to listen on Quad ’57s, starting in 1973 when I bought my first pair (and still have that pair, restored now in use in a second system).
Attack and decay of piano has always been important to me since that was my primary instrument and I have a better sense of how the system performs listening to well recorded piano. Many recordings are very challenged on this front.
Soundstage, tone, bass tautness, spatial placement of instruments, are, to me, all just further attributes that describe but don’t entirely inform the ’it sounds real’ illusion. I’m less interested in hyper-detail and more interested in the presentation of the instruments in real space, with body and dimension.
The ’flow’ that FolkFreak mentions is something that was like throwing a switch when I installed Lamm SET amps- no sense of mechanical reproduction machinery at play, but that improved more with a better phono and line stage, different phono cartridge, etc.
So, we can take it apart to analyze the what, how and why of it (which I guess is the only way to describe sound in words), but the end result is like I ’know it when I hear it.’ (I guess this is your question- what is it I’m hearing when I think it’s "right"?).
I tend to shy away from audiophile pablum and the usual warhorses, musically (I guess to each his or her own as far as that’s concerned), but being able to realize this on garden variety standard issue records makes it more meaningful and a little more challenging, given that I don’t want what I listen to dictated only by what sounds best.
Sorry for all the words, didn’t have time to make it shorter, etc.
bill hart
Ease as in the feeling I could easily hear for miles past the speakers into the recording. Like when you sit on a mountain top and feel like you can see the end of the world.

That and smooth tonal balance without extra details.
That, for me anyway is fairly simple question. What I would want is a  system which in my room allows me to hear all that is furnished by the recording on which you will find all of those musical attributes you refer to without editorializing. Easy to say isn't it. :-)
Another way of saying what everyone seems to be pointing out, for me, is that when everything gels and there's a convincing lack of hype in any parameter you care to mention.

With that, the music simply flows and unfolds before me with nary a surprise, unless it's dynamic in nature, which is supposed to surprise. 👍

All the best,

It was when in 1972 I first heard a direct-to-disk LP (Sheffield S-10) that I got a sense of the main failing of hi-fi systems: to reproduce the startling, instantaneous "snap" of live instruments, whether a stick striking a drum head, a piano keyboard being pounded by a pair of strong hands, or one of the strings on an upright bass being yanked on, rebounding and bouncing off the neck and creating a "buzz". Finding components that excel at that ability has long been a priority for me in system building (the other being lifelike timbre, the lack of vowel coloration).

Equally important is the "inter-transient silence" (as J. Peter Moncrieff of IAR called it) between notes, which throws the notes themselves into high relief or contrast.

These two criteria very much effect the sense of musical timing and flow, important to the above advanced audiophiles. They are also very instrumental in the creation of transparency, the freedom from added veiling and texture (not the texture of the reproduced instruments, but texture added BY the system). The irony is that good systems today are much more transparent than are the vast majority of recordings we play on them! The sound quality of recordings is now the major bottleneck in the reproduction of music.

@bdp24 +1! Your observations on snap, silence and veiling are absolutely spot on. I’ve spent many years building a system that was as transparent as I could make it using my Sheffields as the standard reference measure. When those Harry James trumpet notes rocket through your brain, you know you’re on the right track. The quality of the source material is an essential part of happy listening!
@whart +1

When it's right and real sounding, it's either all too hard or it's all too easy to list all the individual things that matter. When you know you're there, it's really a total result overall.

Dynamics (macro/micro), Texture and Timbre,  are important to my ears.
Specifically, a Jazz drummer 's use of brushes on the skins.

Happy Listening!
The quality of the recorded music...composition, performance, sound quality.  Is it interesting?  Is it emotionally engaging?  Is it well executed? Wish I could do a better job defining the characteristics that draw me back repeatedly to certain music.  Regarding sound quality of the recording: clarity/lack of noise/distortion, stage depth and width, imaging and image density, frequency range and dynamics (and that order should not be taken to indicate any sort of prioritization).  The music itself (composition, performance and sound quality) is the 800 pound gorilla in the room that doesn't get enough discussion.  A good recording can make a mediocre system sound great.  A poor recording can make a great system sound mediocre.   
Imaging,bass detail,soundstage.impact ,highs,midrange and great bass are all important to me.My system does it all exemplary.
Hey Folks.  Thought I'd catch us up a bit.  This was my first attempt posting a topic, and missed a bit of clarity in the goal.  Thanks to those sharing so far!  Rephrased, "In improving the sound of your system, define the one thing stands out as the most vital to your progress?"  Spearheaded by the thick little audio journals of the late 70's, Harry Pearson and J Gordon Holt gave voice to hi-fi.  We've become quite skilled in the language of sound; in defining macros & micros, stage presentations in halls and the nuances of studio production..."inter-transient silence" is a fine example from above. 
In "the chase," my personal niche is obtaining the gear best I can afford, then going to work improving upon it.  Removing harmful resonances both of cabinetry and under the hood of all my gear has lifted the resolution to incredible heights over the years.  The trick is, keeping all that imagery musical, and in place.  Here, latest upgrades have been in the electrical realm, further refining my 10ga dedicated line with new outlet/cover and hard wired male plugs.  So far, results are more than the leading edge transients, and/or decay, or "air around the instruments," more than "flow," "organic," "ease," "Sheffields"  --Thelma Houston's, "I've Got the Music in Me," circa 1975 was my first, btw.--  It is, of course, the sum of all that...yet, timbre is what hits me first and truth.  Onward!  Pin
 " a good recording can make a mediocre system sound great "

No way it can.

its cool to be verbally expressive, yet I feel life ingeneral is far more simplistic and few words are needed to actully convey what it is about a system which indicates it is doing what we want….

is the mouth open? if sitting, are the knees bobbing up and down with the music? do you not want it to stop? if the outfit is yoru’s do you look forward to turning it on?

those are what I look for as the end result which says, “feel free to exit the treadmill now:”

as for the shortest path to improving the audio fidelity in a stereo rig, I’ve always thrown my hat into the ‘SOURCE’ camp.

every substantial source upgrade has yielded the most benefits.

this indicates as well that all else in the system is already very good to excellent.

however, on average most folks do not own ‘destination’ rigs, and as such their rigs are usually in flux, if not entirely fluxed outright. I’m sure many of my former arrangements were in ‘process’ the majority of the time. maybe, always.

the front end first approach allows one to invest less in speakers too. its impressive what having $50K in front of $10 or 15K speakers can do! even with <$10K speakers the sound is ordinarily superb.

as for sheer impact, its gonna be all about the loud speakers specifically. make a major move there and things will change the most. everytime!

which way things change is the sole caveat.
I built my ($8k) system not to ’scale the summit’ by itself, per se, but primarily to avoid all the usual sorts of mistakes that I saw being imposed by manufacturers in the name of "costs", "practicality" or the "traditional approach" based more on what they see that people buy, not on what they might actually benefit from (I went open baffle [DIY] instead of boxed and with active [fully adjustable] electronic crossovers). Then I, too, started to dig down on improving what I had...noise floor reduction, EQ, delay, grounding, etc...and later this year will be adding a dedicated listening room onto the house. I've spent more on "tweaks" than I have on the system.

Right now, just a total falling away of colorations, lack of clarity, etc and everything here has taken such a complete step forward, that the "gulf" that has always existed between me and the performers has not just diminished, but has actually been erased.

Hopefully by the start of 2021, I think I will have just found my "exit".