K.N.
Don't know about brands but DEFINITELY cool mist. Should your little one get croup or have any sinus swelling, a warm mist just makes things swell more & makes it harder to breathe. Cool mist keeps his nose, throat & sinus passages moist, without increasing swelling. And, if you have a child who wakes in the night with a cough & you want to take them into a steamy bathroom, DON'T. If there are any respiratory issues (croup, asthma, etc.) the hot steam aggravates it.