Easily solved mystery: it’s a good choice for people who wanted Abigail but worry about it being too common. Abby is to Abigail as Addy is to Adelaide. You see the same thing with names similar to Ava as well.
I like to name characters things that are less than ultra common but not bizarre, so feel free if any of these strikes your fancy.
Girls:
Jacey
Quinn
Kylie
Arden
Calla
Blythe
Autumn
Delaney
Boys:
Landon
Ezra
Ari
Jeremiah
Cole
Avery
Great minds think alike. I also chose Kylie.
I like Jasmine, so you can call her Jazz.
Or Penelope Candace, so you can call her Penny Candy.
My son and his wife aren’t going to be using Imogene Freya after all so feel free. Just as I was getting used to it, they found out it’ll be Maxwell James.
My favourite girl’s name is still Alathea, after the Robin Trower track. Never met or even heard of one, and it doesn’t rank in the top 1,000
I don’t really have a favourite boy’s name, but you can’t go wrong with Jack - one syllable and #42, so not strictly in the guidelines, but still. Jack.
See, the problem with this is that there is probably an inrush of Williams and Kates and Pippas and Harrys these days, named after the royals.
Apparently my name was a popular surfer-dude name back in the early sixties, so I got stuck with it, even though I am–how shall I say it–most emphatically not a surfer dude.
Those kids will grow up in classrooms where they are William #3 and Kate #4, just as when I was small, I was surrounded by Scotts and Mikes and Kathys and Debbies…
Don’t plan on ever having children, god forbid I’d get convinced otherwise, but I like naming. Boys : Fléance, Achille, or August, and for girls : Émilienne or Mathilda (Matty).
Kylie is red hot popular right now. Like barfening popular, fer sure.
Oonagh
Petra
Simone
Florence
Alfie
Tobias
Ignatius
Otto
Richard ( call him Dickie)
Gilgamesh
Always been partial to the name Bodicea (boe DEE see yuh) <yes there are several variations of that name and more than one pronunciation I know>myself for girls names, 3 boys, no girls, such a shame, boys names, geez, ummm, I dunno, im pretty much a stick in the mud for boys names, perhaps milesius?
Sylvia
and
Zathras
If you have ten you can name them all Zathras, all pronounced slightly differently.
How about Morrocan or Monroe? Names for a Boy and Girl, birthed by Mariah Carey. (JK)
Two popular Irish names - and both easy to pronounce, unless you are a foreigner of course…
Caoimhe for a girl
Iarfhlaith for a boy
I know an Alaric, who was named after a king.
Hey, OP, give us some input - all of these suck, some of these suck, a few of these suck, none of these suck and here’s why. In a baseball analogy, if you can. Who’s handed you a home run name? Who struck out at bat?
If I ever have a son, I’m seriously considering giving him the name Didymus, after Thomas the Apostle (aka Doubting Thomas). Well, as a middle name. I always figured that the middle name was the appropriate spot for using wildly uncommon names like that: That way, the kid has the choice of ignoring it or using it. For first names, I tend to prefer the boring sort of name like “Michael” or “Peter” or “Mary” or “Elizabeth” that you’re not looking for.
For a girl, my top choice for a middle name would be “Tinuviel”, after Tolkien’s character Luthien Tinuviel (it means “Nightingale” in Elvish).
And I probably wouldn’t use this one myself, but I knew a girl named Kunegunda in college. Apparently the original Kunegunda was a Polish saint.
I found a name in a series of novels and really liked the sound of it for some reason.
Nimashet.
It is obscure enough that I couldn’t find a meaning for it, but making an inference from the closest match, it may be intended as “Little Princess.” If you recognize the novels, you will also see that this has a bit of irony, if so. 
It might gain some popularity among the Sci-Fi geeks, but obviously isn’t widely distributed.
It wouldn’t surprise me in the least to see Alaric become much more popular in the next couple of years, though: it’s the first name of a character on The Vampire Diaries. (Though, to be honest, until a few episodes ago I thought they were saying Eric with an attempt at a southern accent)
Banhammer
George Foreman (even if it is a girl)
Shithead (it’s pronounced Shi Thayd)
Jayne (but only if a boy)
Please do not make your baby’s name anything the least bit unusual unless you want him or her to be picked on all through school. Of course if your kid is planning to attend Beverly Hills High then go ahead and name them whatever you want. 