I like both but I slightly prefer [name_f]Madeline[/name_f]. It’s easier to spell and pronounce. [name_f]Madeleine[/name_f] is pretty but there are a ton of different ways to spell it and I imagine that may be bothersome for you and baby as she gets older. I also have the association with the [name_f]Madeline[/name_f] shows and books that make it feel young and sweet although I can also easily picture it on an adult as well. I think either name goes great with big brother [name_m]Louis[/name_m] too.
I like both but I would choose based on the pronunciation you want. In Australia [name_f]Madeleine[/name_f] is the usual spelling and it’s pronounced Mad-uh-luhn. [name_f]Madeline[/name_f] is pronounced Mad-uh-line in Aus, but I believe it’s usually Mad-uh-lin in the US.
My preference is [name_f]Madeleine[/name_f], and it’s lovely next to [name_m]Louis[/name_m].
I think [name_f]Madeleine[/name_f] works best with [name_m]Louis[/name_m], and when I see it spelled this way, I pronounce it Mad-eh-[name_u]LAYNE[/name_u], which is oh-so-lovely. I don’t like the sound of Mad-eh-[name_f]LINE[/name_f].
I’ve always preferred the sound of [name_f]Madeleine[/name_f], but sleek [name_f]Madeline[/name_f] does seem to pair slightly better with brother [name_m]Louis[/name_m].
[name_f]Madeleine[/name_f]! [name_f]Madeleine[/name_f] and [name_m]Louis[/name_m] are amazing, and I love [name_f]Madeleine[/name_f] [name_f]Elise[/name_f] and [name_f]Madeleine[/name_f] [name_f]Claire[/name_f].
Good luck!
ETA: [name_m]Just[/name_m] saw you’ve decided on [name_f]Madeleine[/name_f]–yay! [name_f]Madeline[/name_f] is super pretty, but I can’t figure out how to get the len/lyn ending out of -line! I know there’s [name_f]Katherine[/name_f] that does this, but [name_f]Madeline[/name_f] will always be mad-eh-line to me! [name_f]Madeleine[/name_f] and [name_m]Louis[/name_m] will be so perfect together! All the best!