My btw Jap. bantam is an excellent layer. She will lay for around nine days straight then take one day off. When her and my WL hen were first laying we used to laugh and say a little bantam was a better layer then the WL. She was.
cochins are great layers, they lay almost everyday, once the hen is about a year old the eggs are pretty decent size. Also my dutch hen is great too, she rarely skips a day. She is pretty small but the cochins are bigger
Although quail aren't chicken, they do lay bantam sized eggs. They are supposed to be easy to raise and have small space requirements. If you are simply looking to produce lots of bantam sized eggs, you might want to consider quail.