I've got the Johnson A19 (analog)
. This is the analog one. Pretty simple gadget. There's a dial on the front. Dummy proof, especially if you get it pre-wired.
I also have a Control Products Dual-stage controller.
It is far nicer than the A19. It has two 30A relays for both hot and cold control. So, you can plug your freezer into one side of it, and a small cheap ceramic heater into the other and it will maintain your temps year round (see second link for the heater I'm using).
I will say that it is a chore to wire. I do this for a living so I knew what to do and got it right the first time - still took me 30 minutes of carefully stripping wire, etc. But for the novice without any tech skills, this might be a problem.
Programming it is straightforward, but still not as easy as the A19 (which requires no programming).
The Johnson A419 (digital)
is probably the best single-stage controller that does not require a bunch of wiring.