First playthrough (still ongoing actually, real fun trying to marry everyone off while building a street pass team) married Lucina. I liked her character, but then again I liked a number of the female characters. She won out because of aether. Currently have a Morgan with Aether, Ignis, Astra, Pavise and Aegis. I'm typically more worried about Chrom dying when he has a healer following him than Morgan when she runs into the middle of the enemy by herself.
My second playthrough will be with a female avatar on lunatic classic (since hard wasn't all that difficult). Plan to marry her off to Chrom, again for Aether, but also to see how the dialogue changes.