I wanted to love my Favorelles, but they were too mellow to mix well with my other birds. I have one remaining sweet Favorelle hen, and won't get more unless it's a single breed flock. Yes, it's important to consider temperament; the sex-links and RIR's tent to be more aggressive in a mixed...
I also think that ordering a mixed group of birds will be the best idea; What looks good on paper may not appeal to you at all in person. I love the Speckled Sussex hens, and have no use for Barred Rocks; different strokes for different folks! Mary