Grunt has played with this quite a bit. He'll be able to give you 'real' advice. I have nothing of any value to give you.
Having said that, from what I've read (as I have not heard, yet), the two have distinctly different sonic characteristics and have very different effects. From what I've gathered by summing all the opposing opinions, is that there are very strong opinions from both camps thinking either the height or the width, or the combination of both is best.
So in other words, you'll get a bunch of opinions which will not help you much. You're better off just trying each and seeing what you prefer.
