I think the best marrige for Chrom is FeMu. Because if FeMu is the mother of Lucina, it's gives her acess to a ton of classes and skills, including, Galeforce, and you'll be able to reclass her to Grandmaster so she'll get Ignis. And if Chrom is the father of Morgan, it makes Morgan really powerful! And he'll get Rightful King from Chrom. Plus Chrom and FeMu's support conversations are just hilarious and romantic! And if you have them talk to each other if thier married in the Summer Scramble DLC map, it's really romantic! Plus thier marrige changes the storyline a lot, and in my opinion, also makes the storyline a lot more exciting and interesting! FEMU + CHROM 4EVER! XD