I have Ranco and Johnson both. Prefer the Ranco for +/- 1 degree accuracy and easy set features. The probe is also smaller than the Johnson and fits in 1/4 inch thermowells. No complaints - have 3 Ranco for fermentation controllers and use my two Johnson's on my kegerator and fermentation chamber ambient control.
Kegged: Waldo Lake Amber, Notty as Helles, Vanilla Porter, Sweet Stout (nitro), NB Surly Furious Clone, Petite Saison D'ete, Le Seigle Belge Saison, BM Cream of 3 Crops, Edworts Apfelwein
In Process: Braggot
Upcoming Brews: Surley Furious Clone, Uintah Wyld