Rosa - like it. Strong, simple, feminine
Reenie - not keen. Unpleasant sound to me and doesn't seem like a name in its own right (though not sure what it would be short for)
Marnie - not overly keen but nothing against it
Margot - dislike. I don't like the sound at all.
Peggy - not keen. I think this has a slightly ugly sound too.
Nora - I can't take this one out of old lady territory.
Adie - not keen but really like Ada.
Dolly - cute as a nickname for Dorothy but not as a standalone.
Dora - quite like it. Don't know why when I think of Nora as old lady but Dora seems cooler somehow.
Effie - love it! Possibly more of a nickname (Elizabeth?) but I think it works on its own.
Avie - not keen but like Ava
Dottie - not keen. It's like you're calling your child crazy.
Winnie - dislike. Mostly because I don't like Winifred but also because it sounds like a horse.
Ira - I thought this was a boys' name to be honest?
Olive - really dislike this for some reason.
Rose - like it. Very classy and not too common as a first name.
Remy - really like it.
Lottie - not keen as a standalone. Love Charlotte.
Marlow/Marlowe - quite like it. Different. Modern.
Iris - love it.
Primrose/Prim - quite like Primrose. Not Prim.
Orla - not keen.
From your list, my top three would be Effie, Iris and Remy.
Other ideas on the same lines as yours:
Alba, Aphra, Ama, Astrid, Bronte, Blythe, Cleo, Cora, Celest, Clarice, Dulcie, Delphi, Etta, Enya, Edie, Enid, Faye, Freda, Greta, Honor, Hazel, Ida, Inez, Ingrid, Josette, Joy, Kate, Lilith, Lindy, Leonie, Mabel, Maeve, Misty, Noa, Nyah, Nova, Nell, Nina, Opal, Romy, Riva, Rhona, Saffy, Sadie, Serena, Tess, Trixie, Tansy, Una, Viola, Vashti, Willa, Yvette, Zillah, Zelda