Cowboys live on the bleeding edge of technology and, therefore, tend to bleed at times (normally in the form of overtime). Of course, with risk comes reward. In software development this is increased productivity, more robust products, and programmer happiness.
Farmers, on the other hand, represent stability. They are willing to use the same tools, year after year, and normally produce steady results. They are the risk averse -- willing to do twice the amount of work with a tool that is comfortable rather than try a tool that is more specialized and/or capable.
Obviously, we need some sort of a balance between the cowboys and the farmers. Too much of either type is a recipe for destruction. However, I'm certainly a cowboy. I love learning new tools, especially when they get the job done better than the old tool.