I am on the same journey for a whole house humidifier, did some extensive research and here is what i am going with: Honeywell TrueSTEAM 12 gallons HM512.
http://yourhome.honeywell.com/home/Products/Humidifiers/Whole-House+Steam/Whole-House+Steam.htm There are pluses and minuses of steam humidifiers but to my personal opinion the positive side overweight's negative.
Negative: more expensive then others humidifiers(drum, bypass, fan powered, mist); recommended to have dedicated power line due to high power consumption (1kW - 1.8kW depends on model); will increase your electrical bill (can't find any numbers but just logically thinking how much energy will require to convert 12 gallons of water into the steam on daily bases); requires professional installation, but with honeywell it is not a brainier if you ever done any pluming work.
Positive: Does not require pads as other humidifiers which leads to cheaper maintenance, no mold, easier maintenance (spoke to couple friends who has bypass and fan powered humidifiers and both said that during heating season when humidifier is used they buy packs of pads because it's really hard to clean them from water crystals or you need to install water softener filters).
The reason for Honeywell brand is to use one thermostat for all (heat/air conditioner/humidifier) and if you worried about new wire they have RedLink version of it which is wireless more expensive but available.
I hope it will help you to make proper decision.