Zojirushi - EE-TB60

If you want to cover an entire floor, you'll need a top-performance humidifier for each. In Japan, the size of a floor is measured by the number of tatami mats. The Zojirushi EE-TB60 covers up to 17 tatami mats in ideal conditions for a concrete structure, and up to 10 tatami mats in ideal conditions for a wooden structure. It seems like you're comparing them based on price, but be careful, as consumer products in this genre from brands other than Zojirushi are significantly inferior in performance. It's a good idea to start by placing one on just the main living room floor.

EE-TB60 is great, but it will cover a bedroom, or at most a living room/ dining room. To cover a three floor house you would need three of them. And that would be a pain to refill three a couple of times a day. 

I’ve done research and found the “safe” ones to be those which boil the water like a rice cooker - So, we have Zojirushi ones since I find them to be trustworthy and they know a thing or two about engineering that. We still have to clean em out every once in a while but feel much better about it vs the ultrasonic ones (those are really bad for you, as you found out )