When choosing gloves you need to determine each person's needs. For children, mittens are the best option. For very young children there are mittens that have a zip in them which makes it so much easier for the child to get them on and off. Choosing mittens with a cuff on them and a Velcro strap gives you more protection and warmth from the cold and wet.
Mittens will be warmer than gloves and if you get very cold then mittens are the way to go. Some gloves have a zip pocket in them so a hand warmer can be secured into them, these hand warmers will last up to 7 hours once activated. Try to look for Gortex or the equivalent waterproof glove as there is nothing worse than wet and cold hands.
Once you have decided on gloves or mittens then there are varying options of the different types and quality. Try on a few different styles as they can feel quite different and there needs to be around a centimetre extra length from the end of the fingers. If the glove is too tight then they won’t stay as warm, there needs to be a bit of room and movement in them to circulate your body heat.