Daphne [name_u]Maria[/name_u] by far!!
Seren [name_f]Victoria[/name_f] is second
Daphne [name_u]Maria[/name_u] is perfection!
I really like all of the options, but I’d choose [name_f]Daphne[/name_f] [name_u]Maria[/name_u] for you since 1. the meaning in general and the meaning to you are awesome (I love [name_f]Daphne[/name_f] [name_f]Du[/name_f] Maurier too!) and 2. it sounds the best with [name_m]Truman[/name_m]. [name_f]Daphne[/name_f] is on the rise as a name and the Scooby Doo association is not nearly as strong as it used to be anymore. I love it.
[name_u]Seren[/name_u] [name_f]Victoria[/name_f] would be my combo preference, but I’m not loving it for the nickname [name_u]Stevie[/name_u] (seems really forced when [name_u]Seren[/name_u] is already short). Also, I know someone named Serrin and everybody on the phone or who she just meets calls her [name_f]Sarah[/name_f], no matter how much she corrects them. Then, they’re confused and think it’s [name_f]Karen[/name_f]. She has considered changing her name it’s gotten so bad. [name_m]Just[/name_m] a heads up. 
I really think you can’t go wrong with [name_f]Daphne[/name_f].
Getting ready to name our little one [name_f]Daphne[/name_f]. So my vote goes to [name_f]Daphne[/name_f].
I’ve found that the Americans I’ve asked (including myself) have a hard time saying [name_u]Seren[/name_u] with the correct welsh pronunciation. I think it’s pretty in theory but I prefer [name_f]Daphne[/name_f]. I think [name_f]Daphne[/name_f] is so underused but so quirky and feminine!
Daphne is lovely! [name_f]My[/name_f] best friend from uni is named this except spelt [name_f]Dafne[/name_f] but goes by Daf. The “ph” sound doesn’t exist in our language so all names like [name_m]Stephan[/name_m], [name_f]Stephanie[/name_f] with the “ph” turn into “f”. I don’t know if it’s because I’m used to it but I really like the [name_f]Dafne[/name_f] spelling a bit more
She’s also the only one I’ve ever met and she was the only one in our class.
It’s such a beautiful name, very easy to pronounce and it just has an overall sweet and gentle vibe
Oh also forgot to say we pronounce it as daph-neh instead of daph-nee so not sure if my opinion really works for how you’d use the name [name_f]Daphne[/name_f] but hope it helps!
Daphne [name_u]Maria[/name_u] has my heart! I love it, and she gets my vote. [name_u]Stevie[/name_u] is a fun and unexpected nn, and works in both combos—of the two, I prefer [name_f]Victoria[/name_f] I think. I know of a family who have a [name_u]Stevie[/name_u]-[name_f]Joy[/name_f], which I think is adorable (named after daddy [name_m]Steven[/name_m]), but nothing tops [name_f]Daphne[/name_f] [name_u]Maria[/name_u] for me—she’s absolutely brilliant!
All the best!
I like both names seren and daphne! I highly dislike [name_u]Stevie[/name_u] as a nickname.
I prefer the name [name_f]Daphne[/name_f] over [name_u]Seren[/name_u]. I’m American and would not know how to pronounce [name_u]Seren[/name_u] so that’s part of it for me. The suggestion of [name_f]Daphne[/name_f] [name_u]Valentine[/name_u] above is my favorite but [name_f]Daphne[/name_f] [name_u]Maria[/name_u] is also lovely.