I know that they're too old now, but if you have chicks in the future, evidently you can feather sex 4-5 day old buckeyes (normally feather sexing is done on day olds).
They look like hens to me. Roosters get very long thin feathers around their neck, almost like a mane.
Talking with the breeder I got my buckeyes from, they're rather difficult to sex.
Ethel is the only one that may be questionable from what I can see. Her waddles seem a little larger...