Estaleen- I don't like the sound of this. It sounds very frumpy.
Nellie- Cute as a nn for Eleanor, Penelope, etc. I suppose it could stand on its own. I do, however, think Whhooooaaa Nellie!
Lulu- This is a nickname-only name. Beautiful for Lucia, Luciana, Lucy, etc.
Madeline- Lovely! I'd love to meet a little Madeline.
Hazel- GORGEOUS! One of my favorite names ever!
June- Meh. Strikes me as boring.
Ruth- I like it a lot! Very pretty and sweet, with personality.
Elizabeth- Who doesn't like Elizabeth? You can't go wrong with this name!
Grace- Quite lovely, but feels overused.
Gertrude- Eww. Sorry, but I think of a rude old lady wearing lots of leopard print and red lipstick smeared all over her teeth.
Helen- Love! I like Helena too, but Helen is BEAUTIFUL!
Pretty list! My favorites are Hazel, Ruth and Helen. I also like Madeline and Elizabeth.
Estaleen:It's different, but NMS
Nellie: I love it as a nickname, so cute.
Lulu: I know a young girl with anger problems called this, I'm not too keen on it.
Madeline: I am crushing on this right now!!
Hazel: Very pretty.
June: I love it.
Ruth: Another one if my absolute favourites!!
Elizabeth: Timeless and beautiful.
Grace: A bit of a filler for me.
Gertrude: This is my mother's car's name :D
Helen: I kinda like it.
I would definitely use Madeline, June, Ruth and Elizabeth.
Estaleen - Something about the sound is very "pharmaceutical" sounding to me! Or like a hair product! I do like Estella though.
Nellie - I like it but prefer Nell and even more so Nella. I love Nella and think it's a great nn for Penelope.
Lulu - Much prefer Lula, though it's not really my style. I can see the appeal though. It doesn't stand on it's own to me though. Needs a formal name.
Madeline - Madelines run rampant where I live! I know so many more Madelines than Avas. It became generic-sounding for me long ago.
Hazel - Love! I could definitely see myself using it. (I'm also lucky it's my maternal grandmother's name. Great name and great family connection for me!)
June - It's great. I prefer Junie though and as I nn for Juniper.
Ruth - It's on my list because I love Ruthie. It's a great name on it's own too.
Elizabeth - Prefer Eliza
Grace - It's alright, but I think you have better ones on your list.
Gertrude - I just can't do it.
Helen - Much, much prefer Helena
Estaleen- Never heard of it and can't say I like the look or sound.
Nellie- Love Nellie! Though I probably would use it as a nickname for Nella.
Lulu- Also love! But again as a nickname for something like Louisa/Lucille/Lumi/etc.
Madeline- Meh wouldn't use it but pretty.
Hazel- If I loved it enough I would, beatiful name.
June- Kinda bland.
Elizabeth- One of my least favorite names. Especially with this spelling.
Grace- As a first I think it's so sweet.
Gertrude- Love! Especially with the nn Tru!
Helen- I've been falling for this lately!
I would use Nellie, Ruth, Gertrude, & Helen. Lulu I love but would only use as a nickname.