Billie or Ella? Maria or Renata? Technique or feeling?

@skyscraper So as to properly address your query, I’m curious as to what you mean by, “straight jazz.” What would be an example of such?

@skyscraper 

As far as vocalists go, Ella isn’t “straight jazz.”  When we talk of vocalists of this ilk, (Holiday, Vaughn, Washington, Sinatra, etc.) I don’t consider any of them “straight jazz.” I think of Abbey Lincoln who, by the 1960s, was singing real-deal jazz music with the great Max Roach (her husband).  Brilliant.

Those previously mentioned vocalists are singing the songs of Jerome Kern, Cole Porter, the Gershwins, Harold Arlen, Rodgers & Hart, Irving Berlin, Rodgers & Hammerstein, etc.  

These are some of the greatest pop songwriters in history, but not what I would call jazz.

@stuartk ”an improvisatory language.” That’s not vague at all.

Any kind of fancy, martini-clinking music with improvisation in it? Okay.  

I’ll just wear a tux to my next gig and start scatting and getting all busy with my extemporaneous playing, doing a Katy Perry cover. That’ll be, “jazz.”

Technical proficiency is only another tool that may or may not assist the artist in achieving the ultimate goal: cause one to feel something.

To reduce an artist to a polarized representation of some manufactured binary makes no sense.  If Ella doesn’t make you feel anything, then, there ya go. Problem solved. Is this because she has “too much technical proficiency?”  Either way, it doesn’t matter, because she doesn’t move you. If Mariah Carey moves you just as much as Patti Smith, well, there ya go. Either way, any such judgment on the singers’ technical proficiency is irrelevant.
Feeling is the point.

@stuartk Otis Rush and Roy Buchanan!  Great guitar player mentions!

If we were trying to reach the most legitimate, objectively, empirically-based rankings of certain performers, technical proficiency would have to be taken into consideration.  To stay on the topic of guitar players, while I would never personally (subjectively) prefer, say, Yngwie Malmsteen and Eddie Van Halen to, say, David Lindley or Jesse Ed Davis, I would have to rank Yngwie and Eddie higher. They’re just too good, and their disagreeable music is not enough to trump their obviously superior technical proficiency.

@frogman 

I noted a clear distinction in my initial post of “the ‘60s stuff” in regards to Lincoln.  When I think of jazz vocalists, I think of people singing jazz music.  I don’t consider the likes of the masterful pop songwriters I mentioned to be jazz.  They wrote immaculately crafted 3-minute pop songs.  They may be all fancy and stuff, with someone like, say, Ella Fitzgerald exhibiting incredible vocal prowess and improvisational acumen, but it’s often still fancy pop songs.  She ain’t singing the likes of Parker/Gillespie/Davis/Monk/Mingus/Coltrane etc.

This is why I mentioned ‘60s era Abbey Lincoln as an example of a vocalist singing jazz music.  Perhaps others may provide input in this regard.

That’s how I see it.
Perhaps, in apropos fashion, this could all be “boiled down” to a classic Gershwin line: “you say, ‘potato’/I say, ‘puh-tah-toe’”

@stuartk 

“You seem to be asserting that once jazz musicians tackle “songbook” material, they suddenly (in your mind) morph into something suspect, something lesser, something somehow not quite ‘legit’”

I neither asserted, nor even insinuated any such value judgement on jazz compositions or pop compositions.

I addressed a question in this thread regarding jazz singers.  I am not sure how to define such, as jazz seems to be dominated by instrumental music, and artists’ catalogs like those of Holiday, Fitzgerald, Vaughn, etc. are so heavily populated with pop songs of the ‘20s-‘50s. I don’t see how my language betrayed anything derisive regarding those incredible songs. 
I am, and have been for a long time, a deep lover of those songs. My piano playing over the last year has increased noticeably via my constant digging in to those very songs.  This music is less intimidating to take on as a player than Sergei Rachmaninoff’s or Thelonius Monk’s, but still challenging and simply a joy to study and play. I just love them, and love being able to actually play them now with something that resembles competence.  I am, and always have been, a ravenous, insatiable pop guy.

I consider jazz to be that singular, unique, original music of Parker, Gillespie, Davis, Monk, Coltrane, Mingus, Roach, we could go on and on, and further on into the ‘60s and ‘70s, Coleman, Taylor, Art Ensemble of Chicago, I could go on.  I really get excited by the music of those last three, plus Don Cherry, Roland Kirk, again, I could go on.  
That’s my take.

@chowkwan 

I love that show!  When Glen sings “Gentle on my Mind” and kicks the buh-jeesuz out of the guitar solo, it’s sooooo fantastic!

Is that Jerry Jeff on the far left, in the blue shirt and black hat?

@chowkwan I figured it out, the guy is Bobby Bare.