Well, I was bored so I tried to look the base stats of Lucina if she could have another spouse.I realized I didn't do Anna, would add it later...
First the growth, with the absolute growths, and Lord Growths.
Growth
Miriel
HP Str Mag Skl Spd Lck Def Res
Base 41,7 30,0 23,3 41,7 41,7 66,7 26,7 25,0
Lord 81,7 50,0 23,3 61,7 61,7 66,7 36,7 30,0
Panne
HP Str Mag Skl Spd Lck Def Res
Base 50,0 40,0 15,0 45,0 46,7 63,3 33,3 20,0
Lord 90,0 60,0 15,0 65,0 66,7 63,3 43,3 25,0
Cordelia
HP Str Mag Skl Spd Lck Def Res
Base 46,7 40,0 15,0 40,0 40,0 65,0 33,3 23,3
Lord 86,7 60,0 15,0 60,0 60,0 65,0 43,3 28,3
Nowi
HP Str Mag Skl Spd Lck Def Res
Base 53,3 40,0 21,7 38,3 38,3 71,7 36,7 26,7
Lord 93,3 60,0 21,7 58,3 58,3 71,7 46,7 31,7
Tharja
HP Str Mag Skl Spd Lck Def Res
Base 43,3 33,3 25,0 36,7 43,3 63,3 31,7 21,7
Lord 83,3 53,3 25,0 56,7 63,3 63,3 41,7 26,7
Palne!Lucina is without a doubt the best Lucina; Her modifier are also absolutely amazing...
Nowi gives us the Lucina with thebest Def Growth, and probably HP Growth too, with a pretty good Res growth too. She also have the best Def Modifier (But it's still the worst choice because Nowi...)
Miriel is basically as good as Maribelle, and focus more on Magic than Res... She gives Dark Mage instead of Cleric