2", 2.5", 3.5" and 5" depending on the amount of scraps/fabric I'm cutting up. I have smaller sizes, in various lenthgs, in bags that I use to make small string blocks, piano keys etc.
I use 2" strips for almost all my binding, I like them very narrow as I want the quilt to be the main attraction.
Don't even ask about the squares. but they are cut the same as the strips. I just emptied my Yellow/Gold/Brown bag and sewed a bunch of blocks together and have piano keys ready to go for something.