What do you think of these names? (please judge these as harshly as possible. That would be really awesome)

Annabelle is my favourite

Carina doesn't make me think of a car at all. I think it's lovely, but then I'm an Italian speaker. However, you're likely to get misspellings with Corinne, Corinna, etc.
I like all the names on your list, except for Arielle, Ariella and I think Annabella is a bit cumbersome. Millicent could grow on me.
I prefer Erica with a C, though.

Are these all the favourite names of a single person? It is such a wildly varying list - from fussy and frilly, like the -ella names, to prissy and buttoned up (Millicent, Erica) via dated and not in a good way (Susanah) and makey-uppy (most of the A) names. Usually you only see one or two 'styles' when people put lists on here.

My favourite of your list is probably Helena (hel-EEE-na) but if we can offer variants, I prefer Helen.

Ariella - sounds like areola sorry
Millicent - old lady name
Eliana - Ellia is prettier IMO.
Amynta - never heard that before, doesn't sound very pleasing to the ears.
Annabelle - quite nice, best of the bunch.

No thoughts on the others.

Love serena and Louisa.

I loathe Erika/Erica. So harsh and frumpy.

Helen sounds so short and as if somebody had been strangled whilst trying to say Helena. Anna is too short, Louise is boring and Susan is ok...
To me the 'a' sound on the end makes it sound like someone is saying Helen/Louise/Susan but angrily. When my teen is stroppy she adds an ah sound to everything, Muuum-ah
Annabella sounds like two people. Anna - fine, Bella - fine, Annabella sounds like you couldn't make your mind up.

Helen sounds so short and as if somebody had been strangled whilst trying to say Helena

A famous Helena (many legends about her) is the mother of Constantine, Empress Helena

Change the spelling to Luisa, and call her Lulu - perfect!

I'm afraid I don't like any of the others.

I'm going to commit cardinal sin and not read the thread first.

Carina - I know nothing about cars but a car connection sounds familiar, and I don't mean the 'car' part
Susanna/h - fine name but uninspiring somehow
Arielle - frilly
Ariella - frillier
Millicent - fine name, strong somehow, but also spinster Miss Millicent from Cazalet Chronicles
Helena - good solid classic, can't go wrong
Eliana - sounds modern and made up even though I know it isn't. Plus anything 'ana' ending is very on trend, if that's a concern
Amynta - Aminta or Amynta (I suspect the former) was character from To the Lighthouse, or other Woolf book (too lazy to look up). A good name, far superior to the similar ghastly parody name, Araminta
Serena - Why does that make me think of Disney
Louisa - nice
Annabella - prefer Annabel
Annabelle - prefer Annabel
Erika - ok, not really my taste
Antonia - just ok

Carina - meh
Susanna/h - like it
Arielle - awful
Ariella - even more awful
Millicent - love it
Helena - like it
Eliana - meh
Amynta - no, sounds like my Italian gran offering a mint. Just no.
Serena - meh
Louisa - like it
Annabella - too common, too wet
Annabelle - see above
Erika - too harsh
Antonia - no

I only really like Erika from your list.

But then again, it's always been one of my favourite girls' names.

Thank you for the licence to speak freely! Otherwise I wouldnt say the following...

Carina - better with a K. Quite nice.
Susanna/h - a bit frilly.
Arielle - I also hear Sebastien the lobster/crab.
Ariella - flouncy. Would hate to be called this. Think it is the ranch owning spider in Tree Fu Tom.
Millicent - granny unchic. Millie is OK.
Helena - dull but OK.
Eliana - never heard of this. Another OK.
Amynta - awful. Sounds like a made up take on the horrible Araminta. Also "Amn't a.."
Serena - dull.
Louisa - doubly dull
Annabella - fussy. Hate it. Over popular for some reason.
Annabelle - see above.
Erika - love this.
Antonia - horsey and dull.

Araminta spelt with an i
I know a charming and lovely Araminta

Carina - car
Susanna/h - ok
Arielle - common
Ariella - no
Millicent - yuck... 
Helena - over used, but I do like it
Eliana - what?
Amynta - chavvy
Serena - chavvy
Louisa - lovely
Annabella - lovely
Annabelle - lovely
Erika - God no
Antonia - Beautiful. (Noni for short)?? My favourite perfume is Antonia's flowers

Carina
Arielle
Ariella
Eliana
Amynta
Serena
Erika
Antonia
Don't like any of these.

Susanna/h
Annabella
Annabelle
Louisa
Helena
Why take perfectly nice names Susan, Anna, Louise and Helen and spoil them with 'a's or 'belle/bella's'

Millicent, I like it and Milly. Not Millimetre though

Writing this before reading others' responses, so sorry if I either say the same, or completely contradict!

Carina - not keen, sounds a bit uneducated
Susanna/h - love it, esp with the 'h'
Arielle - no
Ariella - no
Millicent - very St Trinians which could be good or bad depending on whether you like St Trinians...
Helena - beautiful
Eliana - sounds made up
Amynta - the worst name here, sounds like a type of sweet
Serena - love this name
Louisa - beautiful
Annabella - lovely
Annabelle - lovely
Erika - the k makes it harsh
Antonia - no, sounds a bit cheap

*(Aggie!)

Like most of those but not Amynta. My best friend is called Antonia and we call her Ant.
I also like Agatha (Agatha) and Vivienne in case you like either of those

Is ariel actually a boys name? I've never heard of that before