Everyone will have a favorite(s), but you have to think of the characteristics that you need in your flock.
First decide if you want them strictly for agricultural purposes (i.e., eggs or meat), or if you want them to also be pets. If you want them to be pets as well as provide eggs, then you need to consider not just how many eggs you get the first year (the hybrids will always win that contest), but how long they will live, how healthy they will be in the long run, how friendly they will be to your family/children, and if you plan on getting more than one breed, will the different breeds get along with each other. Also, since you live in the Seattle area, you have more of an issue with rain then extreme cold, so consider how easy the breed is to keep clean (I would avoid the breeds with heavily feathered feet, such as the cochins).
If you want them to be more than just egg laying machines, I would stick with the purebred, dual purpose class of birds. The hybrids can be very nice birds, and sometimes quite friendly, but their egg production is so heavy the first few years that they have a very high incidence of cancer of the reproductive tract in many lines, and there are several varieties that only lay for a few years then stop. These are production animals that are specifically developed for one purpose, and unfortunately don't stay healthy and productive long.
The "layer" group of birds tend to be quite flighty and high strung, and are not great for families with young children or close neighbors. These are the leghorns and similar breeds. The heritage versions are not quite as flighty (i.e., a Brown Leghorn will be a better bird than a California White in every category except commercial production), but are still not great pets by comparison.
The "meat" group of birds are hybrids that are developed to reach slaughter weight in 6-16 weeks, depending on the variety. They have wonderful personalities, but are not engineered for long life, so keeping most of these types of hybrids as pets usually ends tragically in less than a year.
The game birds can be good layers, but are often a bit aggressive for young children, and often don't get along with other birds.
So that leaves the dual-purpose breeds. These are the purebred breeds (i.e., not hybrids) that typically lay 180 - 250 eggs per year, remain in production for more than 4 years (although most of mine have stayed in production for 7-10 years, with some decline in numbers with each year), and have enough meat on them that extra birds could be slaughtered for dinner. Most of them do go broody occasionally, some frequently, but usually not enough to cause significant loss in egg production from a non-commercial basis. Most of them tame down quite well, many become true lap pets, and it is rare to see an aggressive hen that is a concern around young children (roosters are more variable).
If you decide to get more than one breed, be sure that the breeds have similar personalities. I have numerous friends that have selected the "assortment pack" of hens, only to find that some breeds tend to bully, and other breeds tend to be bullied. This can create a miserable situation if the birds can't get away from each other.
The breeds that I have loved as both pets and egg layers have been Sussex (especially the speckled ones), Dorkings, Wyandottes, Orpingtons (these tend to be easily bullied by other breeds), Plymouth Rocks, Australorps (amazing egg layers, very sweet to people, but did bully my buff orps), Buckeyes, Croad Langshans (the feet are lightly feathered, but will do well in Seattle if you don't have them on mud), and Brahmas (more feathers than Langshans, but less than Cochins). I have not been happy (from a pet/family aspect) with the Rhode Island Reds, Barnevelders, or Dominiques (however, I know many people who love these breeds, and I have only known each of these breeds from one source, which may have an unpleasant line of each).
There are many books and tables and charts that list the characteristics of each purebred, rating personality, ease of taming, egg production, broodiness, likelihood to bully or be bullied, etc. Once you decide what best fits your needs, start looking for a source of that breed early in the year. If you only want hens, you will need to either buy from a hatchery that sexes their day-old chicks before shipping, or you will need to wait until the chicks are old enough to tell a male from a female if you get them from a private breeder (typically 5-6 weeks, depending on the breed). If you order directly from a hatchery, you may need to order 25 chicks at a time. (Some hatcheries do allow smaller orders, but find out exactly how they handle small orders -- some hatcheries ship the chicks with a heat pack, some just ship out a few chicks knowing that a high percentage will die in transport, and others will only make you pay for the few chicks you want, but will still ship out a total of 25 chicks to maintain body heat, so you're stuck with free live "packing peanuts"). If you only want a few chicks, only want hens, and want babies instead of teenagers, then you can either share an order of 25 from a hatchery with some friends, or get some chicks from a local feed store. Some feed stores have lists of what breeds they will have available on what days, allowing you to plan ahead. Some also have "heritage days", where you can pre-order from a large list of breeds and get exactly what you want. Sometimes deciding where you will get your chicks can help you narrow down what breeds to consider. There's no use in wishing for a rare breed that you can't get.
Good luck. Backyard chickens are wonderful.
