best source for a high quality thermostat

I've seen lots here about the poor quality and inaccuracy of many thermostats. I presume that some manufacturers and some types of high flow thermostats are better than others. What has worked best for you? I'm looking to have a system that produces the least chance of overheating/malfunction in slow traffic on a really hot day. This is not the only part of the system I am trying to optimize, so please keep this to THERMOSTATS Thanks!