Hi! After doing some research I found that the cool mist humidifiers are more healthy since they have a less chance of growing bacteria. I finally bought a hamilton beach cool mist humidifier from Babies R Us. You can put the parts that touch the water in the dishwasher so it stays cleaner. Also it is digital and has a low, high, and quiet mode so it is like white sound and helps my daughter sleep when she is sick. Then you also buy new filters so that way again, it is healthier. I also bought the vicks warm mist that you can add the vicks vapor rub to it, before I had my little girl. I just think the cool mist is better for the little ones.
One more thing if you live where there is hard water the manufacture suggests using bottled water so you don't have to worry about the hard water messing up your humidifier.