JRT have made great foxers, great digger dogs but they have recently become lap dogs.
As a lad in the 70's, I recall my Dad having over 40 JRT's at one stage, and developed a strong line of eager hunters, working as a pack or an individual on badgers as well as foxes. Very agile underground, fearless and relentless agression, but easy to handle/maintain.
However, they did tend to get grumpy with age.