Members have commented that certain manufacturers/builders produce a great neck. To me, that implies that there is an ideal neck that everyone acknowledges is superior to others. With all the variables in neck configuration (contour, width, depth, volute, heel shape, etc.), coupled with individual player variables (hand size, finger length/girth, playing style, etc.) I have to think that the desirability of any particular neck is a function of the sum all these variables (and probably more). Hence, a neck that's great for one player could be undesirable for another. So, in terms of playability, can there really be a neck deemed superior to others? Or, is the playability of a neck dependent on who's playing it?
It's form and content blended, then the player, set up and so forth. Everybody's hands are different, only recently did we get good custom necks, like 1-1/4" wide at the nut. Recently is a relative term, not just a repro or copy neck.
I think when folks talk about great neck makers, it's not necessarily the "shape", although any neck maker who does CUSTOM shaping probably gets kudos.
I've always felt when someone says they got a GREAT neck, they're talking about accuracy in following a pre-war pattern, fit/finish, correct choice of bindings, wood, desired fret width, great intonation (accurate fretting pattern), perfect heel fit against pot and not touching tension hoop, correct stain color, defect free final varnish/shellac/nitro, really good looking wood grain, clean inlay work, perfect nut slots for correct action and tuning, not too whippy or clubby as far as thickness and stiffness, etc.
Even during Gibson's worst years, reviewers like Bill Emerson used to give reluctant credit to them for consistently good "fit and finish", clean binding work, etc.
I make ukuleles and tenor guitars, but I think the same thing happens for all fretted instruments.
Sometimes someone plays one of my instruments and says "This is a really nice neck" (I'm British, so this is probably equivalent to "great"). Usually they play it a bit longer and then say something like "I usually prefer a thinner/fatter/wider/narrower neck, but I could play this one quite happily".
What I think goes on is that a "great" neck is one which feels really good in the hand, encourages you to play and tells you (by feel) that you won't be fighting some characteristic of it which impedes your playing. So it's an ergonomic thing.
I suspect most of us have had the experience of playing a mass-market instrument where, although the neck works adequately in mechanical terms, it just doesn't seem to allow our hand to play it easily. Its shape leads the hand and fingers into slightly the wrong place for playing, and so you need to adjust. Thus it feels slightly awkward.
Obviously a neck has to work mechanically, frets in the right place, strings nicely positioned, etc. But "greatness" is about how it feels to play. I could imagine some player saying "This is a great neck, even though it looks awful!"