I prefer the traditional Madeleine vs the Americanized Madelyn.
Madeline (only 2 Es) will give you the -LINE pronunciation rather than -LYN
ETA: Have never seen the Madelaine spelling before, but agree with PP that it would give you the -LANE pronunciation.
There are rules for spelling/phonics for a reason and changing them changes the name. It doesn't just make it more unique.