From NB’s list probably Isabella, Ella, or Ellie.
Sound-wise maybe Magdalen? Or Adelaide for a bit of a stretch.
Combos with names that NB suggested as being similar for my first and middle names:
Ella Violet
Ellie Rose
London Elizabeth
Ava Josephine
Harper Madeline
Hannah Scarlett
Carter Nicholas
Mason Alexander
Isabella Isabella ![]()
Haha!
[name_f]Serana[/name_f] and [name_m]Casmir[/name_m] 
[name_u]Seren[/name_u] isn’t on the list but that’s my favourite. I love it but can’t use it as it’s too close.
Anyway, my favourites from the “similar to…” list are [name_f]Vivienna[/name_f] and [name_f]Khiana[/name_f], which are nothing like my name so not sure how they got on that list 
I’m not sure I agree with all of the names listed as “similar” names to [name_u]Maria[/name_u], but nonetheless [name_f]Isabella[/name_f], [name_f]Helen[/name_f], [name_f]Emily[/name_f], and [name_f]Alexandra[/name_f] are lovely.
I like just about every variant of my name. I love [name_u]Konstantin[/name_u], not related but similar sounding.
From the nameberry list: [name_u]Marie[/name_u], [name_f]Elaine[/name_f], [name_f]Joanna[/name_f], [name_f]Nicole[/name_f], [name_f]Mary[/name_f], [name_f]Theresa[/name_f], [name_f]Irene[/name_f].
[name_f]Katrina[/name_f]
[name_f]Cara[/name_f]
[name_f]Kaia[/name_f]
The similar names to my full names are all 80’s American charttoppers and so not my style,
Luckily, my NN has plenty of pretty options! [name_f]Eliora[/name_f], [name_f]Hallie[/name_f] (one of my favourites!), [name_u]Baylor[/name_u], [name_f]Emeline[/name_f], [name_f]Lyla[/name_f], [name_f]Bea[/name_f] (which would also work as an NN for my full name!), [name_f]Lilia[/name_f], [name_f]Elvira[/name_f], [name_f]Gracie[/name_f], [name_f]Gisele[/name_f], [name_f]Arleigh[/name_f], [name_u]Elia[/name_u], and [name_f]Nelle[/name_f]!
verita is pretty
From nb’s ‘similar to…’ list, I like Iris, Josephine, Poppy, Cordelia, Ruby, Celeste, & Juliet.
[name_u]Wren[/name_u] 
[name_f]Savannah[/name_f]
[name_f]Helena[/name_f]!
[name_f]Amelie[/name_f] or [name_f]Emilia[/name_f]
There are a lot of good ones that pop up for my name.
[name_f]My[/name_f] favorite
[name_m]Kuiper[/name_m] (love the astronomy connection)
I also like
[name_m]Kepler[/name_m]
[name_u]Aletris[/name_u]
[name_u]Endellion[/name_u]
[name_u]Coriander[/name_u]
[name_m]Daphnis[/name_m]
[name_f]Theophania[/name_f]
[name_f]Juliet[/name_f] and [name_f]Eloise[/name_f] which are, funnily enough, names I would recommend on NB if anyone was looking for a sister for a [name_f]Felicity[/name_f].
Esmeralda!! One of my fav atm
Santiago - would 100% use if not for it’s popularity
Josefina- seen as an old lady name and I don’t like it quite as much as I love Josephine
Can’t say I’m enamoured with any of them, but I think [name_f]Ysolde[/name_f] is the best of a not really my style bunch. Maybe [name_f]Jorjette[/name_f], [name_f]Caili[/name_f], or [name_f]Allina[/name_f] with different spellings, although perhaps somewhat ironically I had to use a variation of my name in the first place haha. I do find it interesting that a version (Jorjina) of one of my grandmas’ names (Georgina) came up.
I like [name_f]Anna[/name_f] and [name_f]Anya[/name_f], and I also like [name_f]Amaya[/name_f] (which is close enough to my real name, I think…?)
From the NB list: [name_m]Maurin[/name_m]! With [name_u]Seneca[/name_u] as a close second.
Personally, I like [name_u]Merrill[/name_u], although it certainly sounds more southern than [name_u]Merle[/name_u].