I just had to read what everyone else considered their favorite tool. I would say first is my rotary cutter. I have several different sizes and brands and I use them all. My very favorite tool is my Eleanor Burns Flying Geese Ruler. I have 2 sizes but use the smaller one to make 6 1/2" variable stars and tons of geese, my favorite block. This ruler makes perfect geese every time! Then, of course, I couldn't live without my Gingher's or my ripper. Worst tool -- not really a tool but those long yellow head pins. They bite big time every time I use them so tacking something on my design wall they usually stay in the box.