Lets see...

I have 1 Herpstat (a very good stat), 2 Johnsons, 1 (in use) Ranco, and 1 ZooMed. I used to have 5 ZooMeds, but sold 4 to folks I helped with setups.

The Johnson, so far, is my top favorite. It's the one that keeps temps the most accurate, even when the heat sources are slightly different (ie small wattage differences).

A note on ZooMed stats: They ARE a good stat to have when you're just starting out or just can't afford the big ones. Yes, from time to time you will find a dud that just won't work, but all you have to do then is return it to the manufacturers for a replacement. All 5 Reptitemp stats I had worked perfectly for over a year. The one I still have is STILL working great. So don't think they're crud just because they're cheap - they're a lot better than a rheostat or nothing at all.