I prefer pie charts. I think they are easier to read, especially at a glance. I also find them more aesthetically appealing. I can much more quickly have an understanding of what percentage each portion holds, as the size of the slice is the percentage. With waffle pieces, I can tell that one portion is larger or smaller, but the proportions are more difficult to quickly ascertain. The waffles are only better if there are lots of tiny parts that are difficult to see in a pie chart. Each piece of a waffle is the same size, while each pie slice is a different size. 1% is easier to see on a waffle than on a pie, but so long as small numbers like that don't appear too often, pies are the way to go.