lus1:For me, my workhorse is a knife that can handle any task without being afraid of chipping it or breaking the tip if I am not careful, that is to say, it is robust, and not too thin behind the edge. I would use it without thinking too much regardless if it is a block of cheese, a steak, fish for ceviche, a bunch of parsley or a tomato. It is large enough for most tasks but not so large that I would not use it for a bit of precision work mincing shallots for example. It can hold an edge for a long time, and not too sensitive to patina development. The profile has a long flat edge as I do not do rocking cuts very often (rarely I do) and instead I do push/pull cuts most of the time. It has a confortable handle, pleasant to the touch and not slippery when wet. It is the knife I reach for when I have people around that are not knife-aware in case they use it when I am distracted. This knife is my Aritsugu A type 210 mm Wa-Gyuto with white color buffalo horn bolster and ho wood octogonal handle.
I think the many criteria listed by Casaluz are as good a definition of workhorse as you're ever likely to get.