Most of the time I use a lens hood. The only cases where I don't are when I just don't have one that works (and I have many), or when I'm using a very wide lens and there really isn't a lens shade that wouldn't vignette (i.e., the filter rim is as much lens shade as there can be).

A lens shade always will give you better results by reducing flare and restricting the image circle of the lens to keep non-image light in the camera to a minimum.