A longer harvest period (and fruits mature in the right months), could be more important than a big production.
Clementines are more sweet than acidic, small, easy to peel and seedless. Children love all of those traits, but take in mind that this trees are vigorous and have thorns and a relatively short harvest period. Clemenules is a good standard variety.
Navel oranges are seedless, much bigger, stand better in the tree without losing a lot of quality and can be more versatile. All navel oranges are good to eat. Some are better for juice than other. Cara Cara is a nice curiosity but Washington is perfect, as Lane Late (late) or Navelina (early)
White Oranges are specially good for juice, but have seeds, and sometimes vicious thorns. Are also more yellow orange than the Navel group. I would pick the former.
Tangerines and Tangors are more acidic than Clementines (a more interesting mix of flavours for some people) and have seeds (that is often a problem with small children). Alternaria is a problem often with Tangerines. The variety Safor is resistant.
Try to provide as many manure as possible in any case and choose carefully the rootstock.