Why shouldn't I use these names?

River- are you a fan of River Phoenix ?
Levi- Bellfield or jeans

Tess - is this is nickname
Juliet - will it annoy you if people spell it Juliette ?
Mila- Mila Kunia fan? Too similar to milia
Scarlet- some people will spell it Scarlett
Wren- unisex name so some people will be surprised that she's not a boy
Eve- Eve/Evie/Eva/Ava are extremely popular and I reckon often interchanged
Hazel - is she likely to have hazel eyes?

I love Tess, Juliet and Sabrina. The latter two are on my list. Teenage witch wouldn't bother me as it isn't a bad association IMO. My father had a great Aunt Sabina which is similar but a little less witchy.

Only comment on your list is Scarlet, it just makes me think 'scarlet woman' or 'Scarlet the Harlot'.

Sadly, I wouldn’t use Tess. It’s the name of an undeniably large nursery assistant, and parents taught a child to call her Ten Ton Tess. Shocking of the parents, but shows it is still current.

You asked for bad associations so for me it's River (Phoenix early death) and Levi (Bellfield unspeakable horrific man)

Juliet also an early death

You do have a very pretty list though so I'm sure you will have options.

Wren - baby conceived in the kitchen ?

Eli - meh
River - pheonix, bit hippy
Levi - jeans

Tess - lovely, good classic name
Juliet - lovely, good classic name
Ivy - bit old lady
Mila - Kunis
Scarlet - O'Hara
Esther - Rantzen, also a bit older lady
Sabrina - Teenage Witch
Wren - little brown bird - meh
Eve - lovely, good classic name
Hazel - bit 1980s but not as bad as some on the list

Levi -jeans
Mila - reminds me of Milia which are annoying bumps on the skin but this might just be me!
Scarlet - fever
Sabrina - the teenage witch

Eli - I like this.
River - Phoenix. Makes me think of druggie deaths
Levi - Bellfield. Or jeans.

Tess - lovely
Juliet - I like this too
Ivy - really nice
Mila - a bit ‘nothing’
Scarlet - wouldn’t use. It’s a lovely name but only works well on girls with dramatic colouring. I know a lot of insipid looking little Scarlets and the names doesn’t suit them at all.
Esther - ok
Sabrina - teenage witch.
Wren - it’s a bird, not a name.
Eve - lovely but very overused for the past 15 years
Hazel - nice, uncommon without being weird.

We used to say 'Scarlet the Harlot' at school

Sabrina is beautiful!

Wren, which has come out of nowhere to be very fashionable right now, is not attractive as a name. Why a wren, rather than sparrow, starling, pigeon? Doesn't even sound mellifluous as a word. Dull

Ivy has also become very popular but it sounds very old-lady ish imo.

All the rest are fine. Tess and Juliet are beautiful, as is Eve (though that's over popular I suppose).

Well you have picked really lovely names, so that makes it hard! The only one I don't like is Wren. You don't pronounce the W, so it just sounds like Ren. Not a nice sound and reminds me of Ren and Stimpy.

Mila reminds me of milia (white spots) and sounds ugly: MEAL-a. The others all seem OK to me and I love Hazel and Juliet.

If I were to pick then River for a boy and Scarlet for a girl

The other names have either too many connotations or are a bit meh

Eli - ok
River - bit naff
Levi - ok

Tess - nice, but isn't it a diminutive of Theresa?
Juliet - love this - bear in mind some people say JU-liet and others Juli-ETT
Ivy - nice
Mila - no, sounds like a milkshake mix
Scarlet - 'scarlet woman' - not for me
Esther - lovely
Sabrina - no
Wren - sounds like a surname to me
Eve - lovely, but there are many
Hazel - nut - so no from me

Witch Hazel.

Just commented on the ones I wouldn’t use.

River- to me is a bit ‘want to be unique’ but in reality I know a lot of Rivers (both male and female)
Juliet- nice as a full name but would worry she would become ‘Jules’ (would push for Lettie)
Mila- pronunciation difficulties?
Scarlet- would get called ‘Scar’ (again-would push for Lettie)
Sabrina-witch

The Wren is my favourite bird. And King of birds according to legends. The others are good. Although Levi - and Noah , Eli etc - somehow remind me of gun toting bible bashers in the Appalachian mountains!

Eli - it's not really a full name. Prefer Elijah
River - love this
Levi - jeans

Tess - of the D'urbevilles
Juliet - okay
Ivy - v. popular right now
Mila - love this
Scarlet - good name
Esther - old fashioned
Sabrina - teenage witch
Wren - bird
Eve - good name
Hazel - boring

I like them all, good choices. However despite being a lovely strong biblical name, I always think Esther is a bit lispy to say.

I always think of ten tonne Tess. No idea where it's from but we used to laugh about it at school when we reading Tess of the d'urbervilles

And Levi Bellfield isn't a nice association but not sure it is a prominent association.
Also wouldn't use River bc of River Phoenix

Eli - biblical, but not necessarily bad
River - Phoenix, again not a bad thing, loved him in stand by me.
Levi - jeans

Tess of the d'urbervilles
Juliet - Romeo & Juliet
Ivy - very nice
Mila Kunis
Scarlet - Cluedo, woman
Esther - Ranzen
Sabrina - witch and possible pole dancer
Wren - love it
Eve - feminine and pretty
Hazel - watership down, but it’s nice

Eli always makes me think of snakes but I don't know why. It just sounds sinister to me.

For me the associations are:
Sabrina- Teenage witch
Levi- Jeans
Esther- Rantzen
Juliet- Tragic
Scarlett- Johansson (Beautiful)
But if they’re names you’ve chosen for sentimental reasons none of them are that strongly linked that it would be more than a fleeting thought….. Except Sabrina!

Eli - should use! Strong and biblical and cool
River - shouldn't use because it's a bit naff and has a child-of-a-z-list-american-celebrity vibe
Levi - should use - see comments for Eli

Tess - should use! Beautiful, somehow a bit vintage feeling but also fresh and fiesty and sweet all at once
Juliet - should use. Pretty, classy
Ivy - shouldn't use. Getting popular to the point of dull - becoming another Evie/Ellie/Lily type name that's getting boring
Mila - shouldn't use - see comments for Ivy
Scarlet - should use! I love the sound of it. And Scarlett O'Hara is cool
Esther - should use! Brave, smart biblocal heroine, what's not to like? Also means star which is lovely
Sabrina - shouldn't use. No nice shortenings. Sab? Not great
Wren - should use. Vintage and pretty
Eve - shouldn't use. Will blend into a sea of Eve/Evie/Avas
Hazel - should use. Pretty, fairly unusual but not unheard of nature name