Cool Mist humidifiers are just hard IMO. 1. Warm Mist humidifiers work by boiling water. This has the downside of... well... boiling hot water hanging around the area. But otherwise, these are the simplest and are only ~$20 or $30. 2. Cool Mist humidifiers try to get around the boiling water issue. Since they humidify at room-temperatures, they're a lot more efficient... but now bacteria / mold is growing constantly.…
I got rid of all mist humidifiers because of residue, noise and some health concerns (no, I am not feeling safe inhaling those fine particles) and I am happy for it.
Most importantly, it doesn't get things wet and it is safe to just leave it 24h.