Window, or float, glass is my medium of choice.  It's even better when it's recycled!  Few glass artists use window glass, because it's not designed for the kiln--it is stiff, it devitrifies, and it's hard to colour it.  Through extensive research and testing, I have been able to learn the particular characteristics of float glass so that I can use them to my advantage.  For some deeply-rooted and secret reason I prefer the creative constraint imposed by these basic materials, and they form the majority of my glass practice.