So I really love the nn Maggie and all of its longer forms, but I can’t decide on which I like best! My favorites are Margaret, Magdalene, and Magnolia. What are your opinions on these and which do you like best? Also what other long forms of the nickname Maggie do you like? 
My personal favourite long forms are [name_f]Margareta[/name_f], [name_f]Magdalena[/name_f], and [name_f]Magnolia[/name_f]. From your list, I like [name_f]Magnolia[/name_f] best. It is so sweet sounding, with a little bit of elegant charm most names don’t have.
I Like [name_f]Magnolia[/name_f] best too! Very pretty and different!
[name_f]Magnolia[/name_f] definitely. [name_u]Love[/name_u] the nickname [name_f]Maggie[/name_f], very sweet.
They are all beautiful! I personally prefer [name_f]Margaret[/name_f] and [name_f]Magnolia[/name_f], but also suggest the [name_m]French[/name_m] [name_f]Marguerite[/name_f] and it’s variations: [name_f]Magali[/name_f], [name_f]Margaux[/name_f] and [name_f]Margot[/name_f].
[name_f]Magnolia[/name_f] would be my favorite. I like [name_f]Magdalena[/name_f] as well.
I love [name_f]Margaret[/name_f]! I would definitely say [name_f]Maggie[/name_f] is a nickname for [name_f]Margaret[/name_f].
[name_f]Magdalen[/name_f], [name_f]Margot[/name_f], [name_f]Margaret[/name_f] - in that order.
I love it as a nickname for [name_f]Marguerite[/name_f] <3
I like [name_f]Magdalena[/name_f] the best! [name_f]Magda[/name_f], [name_f]Marigold[/name_f], [name_f]Margaret[/name_f], [name_f]Magnolia[/name_f], [name_f]Margot[/name_f], and [name_f]Marguerite[/name_f] is how I would rank the other ones. [name_f]Magda/name_f and [name_f]Marigold[/name_f] are really the only ones I like. 
[name_f]Margaret[/name_f], [name_f]Magnolia[/name_f], and [name_f]Margot[/name_f]. Tho I wouldn’t nickname [name_f]Margot[/name_f], and [name_f]Margaret[/name_f] has competing nicknames [name_f]Greta[/name_f] and [name_f]Margo/name_f. So [name_f]Magnolia[/name_f] wins!
I love [name_f]Margaret[/name_f]!
I like [name_f]Magnolia[/name_f] best for its nature vibe and that it’s unexpected as a name. Other possibilities I like are [name_f]Magali[/name_f]/e and [name_f]Marguerite[/name_f] out of the [name_f]Margaret[/name_f] family.
[name_f]Magdalena[/name_f], [name_f]Marguerite[/name_f], [name_f]Magnolia[/name_f] - But [name_f]Margaret[/name_f] is kinda sweet!
I like [name_f]Magdalena[/name_f] and Magalie.
[name_f]Marguerite[/name_f] is my sister’s name! Everyone has always called her [name_f]Maggie[/name_f]!
[name_f]Margaret[/name_f] is a timeless choice and lends the adorable possibility of a little “[name_f]Margo[/name_f]” or “[name_f]Pearl[/name_f]” depending on her personality. [name_f]Magdalene[/name_f] I don’t care for as much. [name_f]Magnolia[/name_f] is absolutely beautiful. I also like the nickname possibility of [name_f]Nola[/name_f]. Adorable!
[name_f]Magnolia[/name_f] is my favorite- gets the nickname you like, lends an alternative ([name_f]Nola[/name_f]), and feels fresh and modern.
Best of luck!
[name_f]Magnolia[/name_f], hands down!
My favorite from your list is [name_f]Magdalene[/name_f] —*a timeless classic like [name_f]Margaret[/name_f] that is as fresh and unusual as [name_f]Magnolia[/name_f].
To avoid the obvious examples (more exotic names like [name_f]Margarida[/name_f], [name_f]Margaretha[/name_f], [name_f]Margery[/name_f], Magna) I love the idea of [name_f]Maggie[/name_f] as short for something like [name_f]Mary[/name_f] [name_f]Agnes[/name_f] or [name_f]Mary[/name_f] [name_f]Augusta[/name_f]. One of my GP names is Magnhild / Magnild.