You should move Exchequer Leghorn down to the "fun and color" list. Mine lays 5-7 eggs a week, but they are small (1 1/2 oz). If you want med-jumbo eggs I'd pick a different breed. Maybe from a breeder they would lay larger eggs, but I believe mine came from Meyer so I wouldn't count on theirs to lay larger than a med. at best.
I've heard nothing but good things about australorps, so I think that would be a good choice for production. And it's hard to beat sex link layers for egg production, although they are probably going to "burn out" faster than other breeds since they are bred to maximize egg production in the first 2 years.
I do love my speckled sussex. They are very friendly, gregarious even. Always the first to come running when I step out the back door to see what goodies I might possibly be bringing them. They get along well with the other chickens and never seem to cause trouble. They are pretty decent layers too, 4-6 eggs a week so far from each of mine, although they are smaller than some might like (about 1 3/4 oz on average). I don't know how you feel about eating retired layers, but sussex are large birds and I imagine they would make good table birds. We call mine "the butterballs" because they are so round and after about 8 weeks they were so much bigger than the other breeds (SLW, Exchequer leghorn, easter eggers).
If you like the look of the columbian wyandotte you might consider light sussex. They have the columbian pattern and the awesome sussex personality.
