Questions on temperature controllers

I am just building another keezer and am looking for another temp controller. I have been using the analog Johnson ones on my previous builds. They work great but both have copper sensors which really look ugly after some time in the moisture. They are coated with that greenish texture of copper. Nothing bad. Just ugly.
A friend of mine seem to have one with a stainless steel sensor which stays clean.
I would like to know if there are any controllers with sensors which are not using copper sensors which get coated after time in moist environment.
I have also seen pics of the analog Johnson controllers with copper and silver colored probes (stainless?). But the description does not provide details.

Also a question on the digital controllers. I am building my kegerator on wheels to roll out on the patio where my bar is. Will the digital ones keep their setting when I unplug them? I don't want to set them again after I rolled them out and plug them back into the outlet on the patio.

Thanks
Stefan

STC-1000 is made for aquariums. Its sensor is black plastic coated.

It's digital and keeps its setting when you unplug it. I use one on my keezer.