The best overnight diapers for babies and toddlers are Pampers Baby Dry, Pampers Cruisers or Pampers Swaddlers.
For babies the Pampers Swaddlers are a good comfortable and absorbent overnight diaper.
For babies of 1 year old or older then pampers baby dry or Pampers Cruisers diapers are good overnight diapers.
My 2 year old wears Gentle Steps Diapers overnight as they are cheap and he wears Pampers Cruisers diapers during the day.
I find the Pampers Cruisers work better for him during the day and at night the Gentle Steps Diapers work better for him because he wets more at night.
I also have a 6 year old son who wets the bed at night and wears the Dollar General Gentle Steps size 7 diapers and they absorb really good for him.
The diapers still fit the 6 year old really good and the Gentle Steps size 7 diapers will likely fit him for another few years if he needs them.