You have a beautiful list! My favourites are in bold.
Agnes - gorgeous, it’s a family name so maybe I’m slightly biased but I love it
Alethea - whilst I love Althea/Athena, this is off for me. I can’t not think Alicia, which I dislike. What about Athalia?
Alexandra - I’ve never liked this, I don’t know why. It’s just long and dull.
Alice - pretty, but it’s so popular in the UK it’s not incredibly special to me.
Augusta - I LOVE this so much.
Catherine - I have a particularly bad association with this, so I’m not a fan. I do love it’s nicknames though (Kitty - ahhk!)
Clarinda - never heard this before, but I like it.
Constance - Beautiful. I know the most gorgeous little girl called Constance which is why I fell in love with it (love Connie too)
Dorothea - I like it, but it’s a bit frilly for my tastes.
Dorothy - Again, I adore this because of one little girl I know (she’s actually Constance’s sister!) I love the literary connection as well.
Drusilla - I want to like this but it’s too witch-y.
Edith - Lovely, especially with nn Edie
Eleanor - So elegant and beautiful but like Alice, I’m a bit bored with it. In the UK it’s usually pronounced el-ah-nah, and rarely as el-ah-NOR, which I dislike for some reason too.
Elizabeth - Elizabeth is such a perfect name, which is why it’s been so popular for so long. It’s massive amount of nicknames keeps it fresh too. But I’m going to be honest, I don’t love it. It lacks a certain quality for me.
Eloise - I appreciate the French-ness of this, and in theory I should like it but I find it a little slimy.
Elsie - So sweet. It’s really trendy in the UK which puts me off, but it’s still lovely.
Eugenie - I think of the princess. Not a great connotation.
Florence - this is beautiful, with so many pretty nicknames (I know a Flo, a Florry and a Flora)
Frances - This was never a huge favourite of mine, but I’ve grown to appreciate it because of Kurt Cobain and Courtney Love’s daughter.
Gwendoline - it’s okay, I’ve never loved it. Aesthetically I prefer Gwendolen(e).
Helena - huh-lay-na or he-leh-na? Like Eleanor, Nameberry seems to say this differently to what I’ve heard! I like the second pn.
Imogen - I like this a lot, but I don’t love it like I used to. It’s perfect on your list though.
Ingrid - so beautifully Scandinavian. I feel it sticks out a bit from the rest, though.
Iris - Iris is a long-term favourite of mine, it’s gorgeous.
Isadora - this was one of my first favourite names so I think I’ll always appreciate it, but I’ve grown to dislike the -dora ending.
Margaret - this is a super important family name for me as well, so again I’m biased. I think it’s a beautiful and massively underused name, with a huge array of nicknames. The only thing that puts me off it that when I do get round to having children, I think it will get very popular very suddenly, in the UK at least, which is a shame.
Philippa - Pippa is a huge favourite of mine, and I know girls who’ve made me like Philippa, but I’m not a huge fan.
Rosalind - I was thinking only yesterday how sweet and magical Rosalind is, but I usually ignore it since I don’t usually like Rose- names. It’s grown on my very quickly, I love it.
Rosamund - another one I usually ignore; the -mund part sounds sort of vulgar to me.
Violet - This is lovely, but I prefer Viola for it’s literary heritage (Twelfth Night is my favourite play, and the one I’m named after).
Philomena - there is a new, very successful Steve Coogan film out called Philomena which I automatically thought of. It’s okay. I can’t not think of Philadelphia Cheese though. Mena is cute. What about Pomeline?
Anywho, regardless, I need some honest opinions towards the following names. The only one set in stone right now is [name_f]Maude[/name_f] 
It’s the only one I haven’t been able to shake.