There's really no best brand of diapers as all kids and babies are different.
One brand of diaper may work great for one kid or baby and others may not.
However a good cheap brand of diapers are the Dollar General Gentle Steps diapers which come in several sizes including a size 7 that can fit a 5 year old and even an 8 year old and sometimes older.
My own 6 year old son wears Gentle Steps Size 7 diapers for bed wetting.
For babies and toddlers either Huggies, Pampers or Dollar General brand diapers are good brands of diapers for them.
If you want a good cheap diaper you can buy the Gentle Steps diapers which average out to about 24 cents per diaper.
The size 7 diapers in gentle Steps diaper brand can be bought for $4.95 for 20 diapers in a pack.
Since my son only wears them at night he only needs about 2 packs of those diapers per month.
So for bed wetting it only costs me about $10.00 per month for his diapers.
When he was in diapers full time at 3 years old he would use 3 to 4 diapers per month and I switched him to the Gentle Steps diapers then as well.
I spent at most $25.00 per month to diaper my 3 year old and would gladly diaper him again as I miss his full time diaper days.
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.