Also keep in mind, hens tend to have the same number of eggs in them regardless of breed, so a leghorn and a polish crested will lay the same number of eggs over the course of their lifetime--the leghorn will just be used up at a couple of years while the polish keeps going for much longer. If you get a production breed that lays almost every day, she will quit laying sooner in her life than a hen who lays less often, so that's the trade-off.
The two most popular chickens with my students have been Chicky Gaga, my buff-laced polish, and Pipsqueak, my old English game bantam. Neither one is known for their egg production, but they are extremely friendly and make great ambassadors. You might consider having a flock of layers with a couple of "odd" breeds for pets, but since every chicken is an individual, it's hard to say what kind of a personality they'll actually have. We got Barred Rocks our first year because we had heard what docile, wonderful birds they were, and instead they turned out to be awful. The rooster was a violent hellion and the hens were neurotic and flighty. We sold them off and avoided BR's for a long time because of that experience, but when we finally gave them another shot, they were just the most wonderful chickens to be had--even the rooster was an absolute sweetheart. I suppose my advice would be to get the breeds you want, and if they turn out to be less than you hoped, sell them or rehome them and invest in different birds. The odds are good that you'll have at least one chicken that is friendly, outgoing, and lovable.
