You can do almost any type of work (or leisure) with almost any type of bike if you really want. So what is your personal preference? How upright do you like to ride, and do you prefer flat bars or drop bars?
Personal preference will overwhelmingly dictate what kind of bike you build. Keep in mind what tires you want so you can make sure that the frame has enough clearance, and what kind of braze-on items you might want.
With this in mind, what kind of riding do you plan to do? What is the weather like, and what kind of add-ons would you like to have?