Which breeds lay the most eggs?
Which breeds to avoid if egg production is important?
A hen does not lay eggs while she is broody. So you should get more eggs if your hens do not go broody. Some breeds are known for going broody frequently, others not so much, but each breed will still have some hens that go broody more than others.
Some hens take the winter off from laying, others do not.
If you want lots of bantam eggs you might get a bunch of bantams, then pay attention to which ones go broody and which ones stop for the winter. You can rehome or butcher the least productive birds, and buy or raise more of the most productive kinds.
You might try some Easter Egger bantams. If you order bantams from a hatchery, the hatchery is selecting for certain traits in each kind of bantam. With the Easter Egger bantams, they will be selecting mostly for colored eggs and laying ability. With the other breeds of bantams, the hatchery should be selecting for the correct feather color and pattern and comb type and body shape and so forth, which means they pay less attention to egg production.
Some breeds (bantam or otherwise) have crests on their heads, that can block their vision. I think muffs on the face can partly block vision as well, but not as badly as big crests do. Feathered feet can get muddy, and I've read that they have a higher chance of getting scaly leg mites. Silkie or frizzle feathers do not provide as much weather protection as normal feathers. You might consider whether any of those traits are important to you: some people love to have chickens with those traits, some people avoid them, some people don't much care either way.
Lastly, breeding. I may breed these birds down the road. I’ve read Seabright roosters can only reproduce in warm weather- any truth to that? I’ve also read the Japanese bantams carry the “creeper” gene.
Japanese bantams: yes, the creeper gene can be an issue. If you breed two birds with that gene, about 1/4 of chicks will inherit it from both parents, and will die before they hatch. Breeding one creeper to one not-creeper will give about half and half creeper chicks and non-creeper chicks, with none that inherit two creeper genes & die of it.
Frizzles should not be bred to each other either. Two copies of the frizzle gene make a frazzle. Frazzles have poor feather quality and often have other health issues as well.
Sebrights have the rose comb gene. A rooster with two rose comb genes is less fertile than a rooster with one or no rose comb genes. So there is a tradeoff when breeding them: either the rooster is giving a not-rose gene to some of his chicks, or he is less fertile. I don't know about the weather part of it (maybe, maybe not.)
If you are willing to breed mixes, maybe start with bantams of several different breeds, and see which hens lay how well. Then raise a son from the best-laying hen, and breed him with the other good layers. Each time you need a new rooster, keep a son from one of your best layers. That is a basic way to increase egg production in any flock, no matter what size or kind of chicken they are. You could do the same thing within a breed, so if you want purebreds that lay well, you could try several breeds and then continue with the one breed that had the most good layers.
You could also mix them with some standard breed that lays well, to increase egg production. Maybe breed a bantam with a Leghorn or a Sexlink (will probably give medium-sized chickens), keep a son from that cross, and breed him with bantam hens. That generation will probably include some medium-sized chickens and some small (bantam) ones. Raise a bunch of chicks, choose the bantam-sized ones, and then see how well they lay.
Which breeds lay the most eggs?
Which breeds to avoid if egg production is important?
We currently sell eggs from our home and at a farmers market. I’ve taken 18 packs of bantam eggs before and people loved them. But with only 2 bantams it takes a while to get 18 eggs
You might also try a few Hamburgs. They are small chickens (but not actual bantams), and they lay small eggs (not as small as bantams lay, but smaller than the common large egg breeds.) Hamburgs tend to be fairly good layers.