I have a small April Aire humidifier. I don't like to add any extra motors, so I really liked this one: no standing water and only one moving part- the solonoid to turn the water on. It works like an evaporative a/c unit. Any water that does not evaporate off of the pad (which you replace annually), goes down the drain. It also came with a humidistat that uses the outside air to adjust the humidity so you don't end up with condensation on a really cold day, plus, it turns it off automatically if the temp gets above 50-degrees.
A unit that has standing water in it and a disk that dips into that water is asking for mold to form. On any of these that use evaporation, you need to replace the media periodically, since they will end up coated with mineral deposits and not work well eventually. WIth the one I have, since it over waters the thing, it dumps concentrated mineral water, so it minimizes the effects.
You'd have to check the specs to see if they have a model that you like that would work with your square footage.