I voted other, mostly because I heard a reference to Louise Brooks the other day and wound up doing some reading and looking up pictures of her. She was extremely cute!
I chose Marlene, but then again I am a Gay man of a certain age.
I’m choosing to answer based only on looks. I’ve never understood how Dietrich was considered attractive. I don’t see it at all. Bow was very pretty. Bow wins.
But Dietrich wore her top hat at a jaunty angle!
You’re moving the goalposts. Tilting them, at the very least.
Louise Brooks or Josephine Baker, by far.
So did Fred Astaire:
https://www.biography.com/.image/t_share/MTE1ODA0OTcxNTQ1NDI5NTE3/fred-astaire-9190991-2-raw.jpg
Of the two named, Marlene
but,
Now you’re talkin’…!
Harlow (1911) missed the cutoff by a year and Theda Bara (1885) by fifteen, so that leaves Myrna Loy (1905). That’s fortunate, too, since I’ll take funny over perky OR sultry any day.
Oh, you have excellent taste. I was thinking of Carole Lombard (who also starred with William Powell) or Greer Garson.
Joan and Constance Bennett. Hubba-hubba! 
https://www.bestmoviesbyfarr.com/static-assets/images/articles/2017/09/joanbennett2.jpg
Bette Davis, when she was hot! :o
I totally could choose in the Firefly quiz, but I can’t here.
Louise Brooks forever!
I picked “other,” because my all-time favorite actress from the Golden Age is Irene Dunne, and from the silent Era, I like Lillian Gish. When I was 17, I wrote Gish a letter, and she wrote me back.
However, I do like both Bow and Dietrich a lot. But I think the edge goes the Dietrich. First, no one else could have managed to capitalize on sounding on sounding sexy while singing so off-key, no one. And Dietrich was a fervent anti-Nazi. That’s how she came to be a Hollywood actress, if you get my meaning. She was also the very first Hollywood star to push US War Bonds. So, call her a one note actress is you want, it still took some guts for her to play the character she played in Judgment at Nuremburg.
Marlene, hands down. Clara Bow seems ordinary, at best, to me. I remember reading that her career ended when the talkies began because she had a really thick (Brooklyn?)accent and I thought “she *looks *like she’d have a really annoying voice” (not that I find all Brooklynites to have annoying voices but hopefully you know what I’m getting at).
Well, hell, if we’re going for slutty I have to vote for Tallulah Bankhead.
LOL, I read slutty instead of sultry. :D:D
Anna May Wong (b. 1905), as sultry as she wanted to be…
https://www.google.com/search?biw=1760&bih=921&tbm=isch&sa=1&ei=LsT9WuDlKo_YzgLF2Y7IDA&q=anna+may+wong&oq=anna+may+wong&gs_l=img.3..0j0i67k1j0l8.111758.112780.0.113586.17.9.0.0.0.0.188.1006.1j7.8.0....0...1c.1.64.img..14.2.278....0.I9HLVCByXXA#imgrc=KSxMHM7JerTQTM:
With Dietrich in Shanghai Express (1932)