best bang for the buck is definitely the WSM. I love mine. As for insulated, I prefer stumps but that is not a water cooker. Though you can just put a water pan in the chamber to add humidity.
2013 Stumps Classic - Delivered 4/15/13
Large BGE - Rescued 2012
2010 WSM 22.5"
2010 Weber genesis gas grill
Rescued 22.5 Weber One-touch gold
BBQ Guru CyberQ
2011 Built UDS - Retired